Add m-esr52 at 52.6.0

1 files changed, 1044 insertions, 0 deletions

diff --git a/gfx/layers/ipc/ShadowLayers.cpp b/gfx/layers/ipc/ShadowLayers.cpp
new file mode 100644
index 000000000..88b88bde0
--- /dev/null
+++ b/gfx/layers/ipc/ShadowLayers.cpp
@@ -0,0 +1,1044 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 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 "ClientLayerManager.h"         // for ClientLayerManager
+#include "ShadowLayers.h"
+#include <set>                          // for _Rb_tree_const_iterator, etc
+#include <vector>                       // for vector
+#include "GeckoProfiler.h"              // for PROFILER_LABEL
+#include "ISurfaceAllocator.h"          // for IsSurfaceDescriptorValid
+#include "Layers.h"                     // for Layer
+#include "RenderTrace.h"                // for RenderTraceScope
+#include "ShadowLayerChild.h"           // for ShadowLayerChild
+#include "gfx2DGlue.h"                  // for Moz2D transition helpers
+#include "gfxPlatform.h"                // for gfxImageFormat, gfxPlatform
+//#include "gfxSharedImageSurface.h"      // for gfxSharedImageSurface
+#include "ipc/IPCMessageUtils.h"        // for gfxContentType, null_t
+#include "IPDLActor.h"
+#include "mozilla/Assertions.h"         // for MOZ_ASSERT, etc
+#include "mozilla/gfx/Point.h"          // for IntSize
+#include "mozilla/layers/CompositableClient.h"  // for CompositableClient, etc
+#include "mozilla/layers/CompositorBridgeChild.h"
+#include "mozilla/layers/ImageDataSerializer.h"
+#include "mozilla/layers/ImageBridgeChild.h"
+#include "mozilla/layers/LayersMessages.h"  // for Edit, etc
+#include "mozilla/layers/LayersSurfaces.h"  // for SurfaceDescriptor, etc
+#include "mozilla/layers/LayersTypes.h"  // for MOZ_LAYERS_LOG
+#include "mozilla/layers/LayerTransactionChild.h"
+#include "mozilla/layers/PCompositableChild.h"
+#include "mozilla/layers/PTextureChild.h"
+#include "ShadowLayerUtils.h"
+#include "mozilla/layers/TextureClient.h"  // for TextureClient
+#include "mozilla/mozalloc.h"           // for operator new, etc
+#include "nsTArray.h"                   // for AutoTArray, nsTArray, etc
+#include "nsXULAppAPI.h"                // for XRE_GetProcessType, etc
+#include "mozilla/ReentrantMonitor.h"
+
+namespace mozilla {
+namespace ipc {
+class Shmem;
+} // namespace ipc
+
+namespace layers {
+
+using namespace mozilla::gfx;
+using namespace mozilla::gl;
+using namespace mozilla::ipc;
+
+class ClientTiledLayerBuffer;
+
+typedef nsTArray<SurfaceDescriptor> BufferArray;
+typedef std::vector<Edit> EditVector;
+typedef nsTHashtable<nsPtrHashKey<ShadowableLayer>> ShadowableLayerSet;
+typedef nsTArray<OpDestroy> OpDestroyVector;
+
+class Transaction
+{
+public:
+  Transaction()
+    : mTargetRotation(ROTATION_0)
+    , mSwapRequired(false)
+    , mOpen(false)
+    , mRotationChanged(false)
+  {}
+
+  void Begin(const gfx::IntRect& aTargetBounds, ScreenRotation aRotation,
+             dom::ScreenOrientationInternal aOrientation)
+  {
+    mOpen = true;
+    mTargetBounds = aTargetBounds;
+    if (aRotation != mTargetRotation) {
+      // the first time this is called, mRotationChanged will be false if
+      // aRotation is 0, but we should be OK because for the first transaction
+      // we should only compose if it is non-empty. See the caller(s) of
+      // RotationChanged.
+      mRotationChanged = true;
+    }
+    mTargetRotation = aRotation;
+    mTargetOrientation = aOrientation;
+  }
+  void MarkSyncTransaction()
+  {
+    mSwapRequired = true;
+  }
+  void AddEdit(const Edit& aEdit)
+  {
+    MOZ_ASSERT(!Finished(), "forgot BeginTransaction?");
+    mCset.push_back(aEdit);
+  }
+  void AddEdit(const CompositableOperation& aEdit)
+  {
+    AddEdit(Edit(aEdit));
+  }
+  void AddPaint(const Edit& aPaint)
+  {
+    AddNoSwapPaint(aPaint);
+    mSwapRequired = true;
+  }
+  void AddPaint(const CompositableOperation& aPaint)
+  {
+    AddNoSwapPaint(Edit(aPaint));
+    mSwapRequired = true;
+  }
+
+  void AddNoSwapPaint(const Edit& aPaint)
+  {
+    MOZ_ASSERT(!Finished(), "forgot BeginTransaction?");
+    mPaints.push_back(aPaint);
+  }
+  void AddNoSwapPaint(const CompositableOperation& aPaint)
+  {
+    MOZ_ASSERT(!Finished(), "forgot BeginTransaction?");
+    mPaints.push_back(Edit(aPaint));
+  }
+  void AddMutant(ShadowableLayer* aLayer)
+  {
+    MOZ_ASSERT(!Finished(), "forgot BeginTransaction?");
+    mMutants.PutEntry(aLayer);
+  }
+  void End()
+  {
+    mCset.clear();
+    mPaints.clear();
+    mMutants.Clear();
+    mDestroyedActors.Clear();
+    mOpen = false;
+    mSwapRequired = false;
+    mRotationChanged = false;
+  }
+
+  bool Empty() const {
+    return mCset.empty() && mPaints.empty() && mMutants.IsEmpty()
+           && mDestroyedActors.IsEmpty();
+  }
+  bool RotationChanged() const {
+    return mRotationChanged;
+  }
+  bool Finished() const { return !mOpen && Empty(); }
+
+  bool Opened() const { return mOpen; }
+
+  EditVector mCset;
+  EditVector mPaints;
+  OpDestroyVector mDestroyedActors;
+  ShadowableLayerSet mMutants;
+  gfx::IntRect mTargetBounds;
+  ScreenRotation mTargetRotation;
+  dom::ScreenOrientationInternal mTargetOrientation;
+  bool mSwapRequired;
+
+private:
+  bool mOpen;
+  bool mRotationChanged;
+
+  // disabled
+  Transaction(const Transaction&);
+  Transaction& operator=(const Transaction&);
+};
+struct AutoTxnEnd {
+  explicit AutoTxnEnd(Transaction* aTxn) : mTxn(aTxn) {}
+  ~AutoTxnEnd() { mTxn->End(); }
+  Transaction* mTxn;
+};
+
+void
+KnowsCompositor::IdentifyTextureHost(const TextureFactoryIdentifier& aIdentifier)
+{
+  mTextureFactoryIdentifier = aIdentifier;
+
+  mSyncObject = SyncObject::CreateSyncObject(aIdentifier.mSyncHandle);
+}
+
+KnowsCompositor::KnowsCompositor()
+  : mSerial(++sSerialCounter)
+{}
+
+KnowsCompositor::~KnowsCompositor()
+{}
+
+ShadowLayerForwarder::ShadowLayerForwarder(ClientLayerManager* aClientLayerManager)
+ : mClientLayerManager(aClientLayerManager)
+ , mMessageLoop(MessageLoop::current())
+ , mDiagnosticTypes(DiagnosticTypes::NO_DIAGNOSTIC)
+ , mIsFirstPaint(false)
+ , mWindowOverlayChanged(false)
+ , mPaintSyncId(0)
+{
+  mTxn = new Transaction();
+  mActiveResourceTracker = MakeUnique<ActiveResourceTracker>(1000, "CompositableForwarder");
+}
+
+template<typename T>
+struct ReleaseOnMainThreadTask : public Runnable
+{
+  UniquePtr<T> mObj;
+
+  explicit ReleaseOnMainThreadTask(UniquePtr<T>& aObj)
+    : mObj(Move(aObj))
+  {}
+
+  NS_IMETHOD Run() override {
+    mObj = nullptr;
+    return NS_OK;
+  }
+};
+
+ShadowLayerForwarder::~ShadowLayerForwarder()
+{
+  MOZ_ASSERT(mTxn->Finished(), "unfinished transaction?");
+  delete mTxn;
+  if (mShadowManager) {
+    mShadowManager->SetForwarder(nullptr);
+    mShadowManager->Destroy();
+  }
+  if (!NS_IsMainThread()) {
+    NS_DispatchToMainThread(
+      new ReleaseOnMainThreadTask<ActiveResourceTracker>(mActiveResourceTracker));
+  }
+}
+
+void
+ShadowLayerForwarder::BeginTransaction(const gfx::IntRect& aTargetBounds,
+                                       ScreenRotation aRotation,
+                                       dom::ScreenOrientationInternal aOrientation)
+{
+  MOZ_ASSERT(IPCOpen(), "no manager to forward to");
+  MOZ_ASSERT(mTxn->Finished(), "uncommitted txn?");
+  UpdateFwdTransactionId();
+  mTxn->Begin(aTargetBounds, aRotation, aOrientation);
+}
+
+static PLayerChild*
+Shadow(ShadowableLayer* aLayer)
+{
+  return aLayer->GetShadow();
+}
+
+template<typename OpCreateT>
+static void
+CreatedLayer(Transaction* aTxn, ShadowableLayer* aLayer)
+{
+  aTxn->AddEdit(OpCreateT(nullptr, Shadow(aLayer)));
+}
+
+void
+ShadowLayerForwarder::CreatedPaintedLayer(ShadowableLayer* aThebes)
+{
+  CreatedLayer<OpCreatePaintedLayer>(mTxn, aThebes);
+}
+void
+ShadowLayerForwarder::CreatedContainerLayer(ShadowableLayer* aContainer)
+{
+  CreatedLayer<OpCreateContainerLayer>(mTxn, aContainer);
+}
+void
+ShadowLayerForwarder::CreatedImageLayer(ShadowableLayer* aImage)
+{
+  CreatedLayer<OpCreateImageLayer>(mTxn, aImage);
+}
+void
+ShadowLayerForwarder::CreatedColorLayer(ShadowableLayer* aColor)
+{
+  CreatedLayer<OpCreateColorLayer>(mTxn, aColor);
+}
+void
+ShadowLayerForwarder::CreatedCanvasLayer(ShadowableLayer* aCanvas)
+{
+  CreatedLayer<OpCreateCanvasLayer>(mTxn, aCanvas);
+}
+void
+ShadowLayerForwarder::CreatedRefLayer(ShadowableLayer* aRef)
+{
+  CreatedLayer<OpCreateRefLayer>(mTxn, aRef);
+}
+
+void
+ShadowLayerForwarder::Mutated(ShadowableLayer* aMutant)
+{
+mTxn->AddMutant(aMutant);
+}
+
+void
+ShadowLayerForwarder::SetRoot(ShadowableLayer* aRoot)
+{
+  mTxn->AddEdit(OpSetRoot(nullptr, Shadow(aRoot)));
+}
+void
+ShadowLayerForwarder::InsertAfter(ShadowableLayer* aContainer,
+                                  ShadowableLayer* aChild,
+                                  ShadowableLayer* aAfter)
+{
+  if (!aChild->HasShadow()) {
+    return;
+  }
+
+  while (aAfter && !aAfter->HasShadow()) {
+    aAfter = aAfter->AsLayer()->GetPrevSibling() ? aAfter->AsLayer()->GetPrevSibling()->AsShadowableLayer() : nullptr;
+  }
+
+  if (aAfter) {
+    mTxn->AddEdit(OpInsertAfter(nullptr, Shadow(aContainer),
+                                nullptr, Shadow(aChild),
+                                nullptr, Shadow(aAfter)));
+  } else {
+    mTxn->AddEdit(OpPrependChild(nullptr, Shadow(aContainer),
+                                 nullptr, Shadow(aChild)));
+  }
+}
+void
+ShadowLayerForwarder::RemoveChild(ShadowableLayer* aContainer,
+                                  ShadowableLayer* aChild)
+{
+  MOZ_LAYERS_LOG(("[LayersForwarder] OpRemoveChild container=%p child=%p\n",
+                  aContainer->AsLayer(), aChild->AsLayer()));
+
+  if (!aChild->HasShadow()) {
+    return;
+  }
+
+  mTxn->AddEdit(OpRemoveChild(nullptr, Shadow(aContainer),
+                              nullptr, Shadow(aChild)));
+}
+void
+ShadowLayerForwarder::RepositionChild(ShadowableLayer* aContainer,
+                                      ShadowableLayer* aChild,
+                                      ShadowableLayer* aAfter)
+{
+  if (!aChild->HasShadow()) {
+    return;
+  }
+
+  while (aAfter && !aAfter->HasShadow()) {
+    aAfter = aAfter->AsLayer()->GetPrevSibling() ? aAfter->AsLayer()->GetPrevSibling()->AsShadowableLayer() : nullptr;
+  }
+
+  if (aAfter) {
+    MOZ_LAYERS_LOG(("[LayersForwarder] OpRepositionChild container=%p child=%p after=%p",
+                   aContainer->AsLayer(), aChild->AsLayer(), aAfter->AsLayer()));
+    mTxn->AddEdit(OpRepositionChild(nullptr, Shadow(aContainer),
+                                    nullptr, Shadow(aChild),
+                                    nullptr, Shadow(aAfter)));
+  } else {
+    MOZ_LAYERS_LOG(("[LayersForwarder] OpRaiseToTopChild container=%p child=%p",
+                   aContainer->AsLayer(), aChild->AsLayer()));
+    mTxn->AddEdit(OpRaiseToTopChild(nullptr, Shadow(aContainer),
+                                    nullptr, Shadow(aChild)));
+  }
+}
+
+
+#ifdef DEBUG
+void
+ShadowLayerForwarder::CheckSurfaceDescriptor(const SurfaceDescriptor* aDescriptor) const
+{
+  if (!aDescriptor) {
+    return;
+  }
+
+  if (aDescriptor->type() == SurfaceDescriptor::TSurfaceDescriptorBuffer &&
+      aDescriptor->get_SurfaceDescriptorBuffer().data().type() == MemoryOrShmem::TShmem) {
+    const Shmem& shmem = aDescriptor->get_SurfaceDescriptorBuffer().data().get_Shmem();
+    shmem.AssertInvariants();
+    MOZ_ASSERT(mShadowManager &&
+               mShadowManager->IsTrackingSharedMemory(shmem.mSegment));
+  }
+}
+#endif
+
+void
+ShadowLayerForwarder::UseTiledLayerBuffer(CompositableClient* aCompositable,
+                                          const SurfaceDescriptorTiles& aTileLayerDescriptor)
+{
+  MOZ_ASSERT(aCompositable);
+
+  if (!aCompositable->IsConnected()) {
+    return;
+  }
+
+  mTxn->AddNoSwapPaint(CompositableOperation(nullptr, aCompositable->GetIPDLActor(),
+                                             OpUseTiledLayerBuffer(aTileLayerDescriptor)));
+}
+
+void
+ShadowLayerForwarder::UpdateTextureRegion(CompositableClient* aCompositable,
+                                          const ThebesBufferData& aThebesBufferData,
+                                          const nsIntRegion& aUpdatedRegion)
+{
+  MOZ_ASSERT(aCompositable);
+
+  if (!aCompositable->IsConnected()) {
+    return;
+  }
+
+  mTxn->AddPaint(
+    CompositableOperation(
+      nullptr, aCompositable->GetIPDLActor(),
+      OpPaintTextureRegion(aThebesBufferData, aUpdatedRegion)));
+}
+
+void
+ShadowLayerForwarder::UseTextures(CompositableClient* aCompositable,
+                                  const nsTArray<TimedTextureClient>& aTextures)
+{
+  MOZ_ASSERT(aCompositable);
+
+  if (!aCompositable->IsConnected()) {
+    return;
+  }
+
+  AutoTArray<TimedTexture,4> textures;
+
+  for (auto& t : aTextures) {
+    MOZ_ASSERT(t.mTextureClient);
+    MOZ_ASSERT(t.mTextureClient->GetIPDLActor());
+    MOZ_RELEASE_ASSERT(t.mTextureClient->GetIPDLActor()->GetIPCChannel() == mShadowManager->GetIPCChannel());
+    ReadLockDescriptor readLock;
+    t.mTextureClient->SerializeReadLock(readLock);
+    textures.AppendElement(TimedTexture(nullptr, t.mTextureClient->GetIPDLActor(),
+                                        readLock,
+                                        t.mTimeStamp, t.mPictureRect,
+                                        t.mFrameID, t.mProducerID));
+    if ((t.mTextureClient->GetFlags() & TextureFlags::IMMEDIATE_UPLOAD)
+        && t.mTextureClient->HasIntermediateBuffer()) {
+
+      // We use IMMEDIATE_UPLOAD when we want to be sure that the upload cannot
+      // race with updates on the main thread. In this case we want the transaction
+      // to be synchronous.
+      mTxn->MarkSyncTransaction();
+    }
+    mClientLayerManager->GetCompositorBridgeChild()->HoldUntilCompositableRefReleasedIfNecessary(t.mTextureClient);
+  }
+  mTxn->AddEdit(CompositableOperation(nullptr, aCompositable->GetIPDLActor(),
+                                      OpUseTexture(textures)));
+}
+
+void
+ShadowLayerForwarder::UseComponentAlphaTextures(CompositableClient* aCompositable,
+                                                TextureClient* aTextureOnBlack,
+                                                TextureClient* aTextureOnWhite)
+{
+  MOZ_ASSERT(aCompositable);
+
+  if (!aCompositable->IsConnected()) {
+    return;
+  }
+
+  MOZ_ASSERT(aTextureOnWhite);
+  MOZ_ASSERT(aTextureOnBlack);
+  MOZ_ASSERT(aCompositable->GetIPDLActor());
+  MOZ_ASSERT(aTextureOnBlack->GetIPDLActor());
+  MOZ_ASSERT(aTextureOnWhite->GetIPDLActor());
+  MOZ_ASSERT(aTextureOnBlack->GetSize() == aTextureOnWhite->GetSize());
+  MOZ_RELEASE_ASSERT(aTextureOnWhite->GetIPDLActor()->GetIPCChannel() == mShadowManager->GetIPCChannel());
+  MOZ_RELEASE_ASSERT(aTextureOnBlack->GetIPDLActor()->GetIPCChannel() == mShadowManager->GetIPCChannel());
+
+  ReadLockDescriptor readLockW;
+  ReadLockDescriptor readLockB;
+  aTextureOnBlack->SerializeReadLock(readLockB);
+  aTextureOnWhite->SerializeReadLock(readLockW);
+
+  mClientLayerManager->GetCompositorBridgeChild()->HoldUntilCompositableRefReleasedIfNecessary(aTextureOnBlack);
+  mClientLayerManager->GetCompositorBridgeChild()->HoldUntilCompositableRefReleasedIfNecessary(aTextureOnWhite);
+
+  mTxn->AddEdit(
+    CompositableOperation(
+      nullptr, aCompositable->GetIPDLActor(),
+      OpUseComponentAlphaTextures(
+        nullptr, aTextureOnBlack->GetIPDLActor(),
+        nullptr, aTextureOnWhite->GetIPDLActor(),
+        readLockB, readLockW)
+      )
+    );
+}
+
+static bool
+AddOpDestroy(Transaction* aTxn, const OpDestroy& op, bool synchronously)
+{
+  if (!aTxn->Opened()) {
+    return false;
+  }
+
+  aTxn->mDestroyedActors.AppendElement(op);
+  if (synchronously) {
+    aTxn->MarkSyncTransaction();
+  }
+
+  return true;
+}
+
+bool
+ShadowLayerForwarder::DestroyInTransaction(PTextureChild* aTexture, bool synchronously)
+{
+  return AddOpDestroy(mTxn, OpDestroy(aTexture), synchronously);
+}
+
+bool
+ShadowLayerForwarder::DestroyInTransaction(PCompositableChild* aCompositable, bool synchronously)
+{
+  return AddOpDestroy(mTxn, OpDestroy(aCompositable), synchronously);
+}
+
+void
+ShadowLayerForwarder::RemoveTextureFromCompositable(CompositableClient* aCompositable,
+                                                    TextureClient* aTexture)
+{
+  MOZ_ASSERT(aCompositable);
+  MOZ_ASSERT(aTexture);
+  MOZ_ASSERT(aTexture->GetIPDLActor());
+  MOZ_RELEASE_ASSERT(aTexture->GetIPDLActor()->GetIPCChannel() == mShadowManager->GetIPCChannel());
+  if (!aCompositable->IsConnected() || !aTexture->GetIPDLActor()) {
+    // We don't have an actor anymore, don't try to use it!
+    return;
+  }
+
+  mTxn->AddEdit(
+    CompositableOperation(
+      nullptr, aCompositable->GetIPDLActor(),
+      OpRemoveTexture(nullptr, aTexture->GetIPDLActor())));
+  if (aTexture->GetFlags() & TextureFlags::DEALLOCATE_CLIENT) {
+    mTxn->MarkSyncTransaction();
+  }
+}
+
+bool
+ShadowLayerForwarder::InWorkerThread()
+{
+  return MessageLoop::current() && (GetTextureForwarder()->GetMessageLoop()->id() == MessageLoop::current()->id());
+}
+
+void
+ShadowLayerForwarder::StorePluginWidgetConfigurations(const nsTArray<nsIWidget::Configuration>&
+                                                      aConfigurations)
+{
+  // Cache new plugin widget configs here until we call update, at which
+  // point this data will get shipped over to chrome.
+  mPluginWindowData.Clear();
+  for (uint32_t idx = 0; idx < aConfigurations.Length(); idx++) {
+    const nsIWidget::Configuration& configuration = aConfigurations[idx];
+    mPluginWindowData.AppendElement(PluginWindowData(configuration.mWindowID,
+                                                     configuration.mClipRegion,
+                                                     configuration.mBounds,
+                                                     configuration.mVisible));
+  }
+}
+
+void
+ShadowLayerForwarder::SendPaintTime(uint64_t aId, TimeDuration aPaintTime)
+{
+  if (!IPCOpen() ||
+      !mShadowManager->SendPaintTime(aId, aPaintTime)) {
+    NS_WARNING("Could not send paint times over IPC");
+  }
+}
+
+bool
+ShadowLayerForwarder::EndTransaction(InfallibleTArray<EditReply>* aReplies,
+                                     const nsIntRegion& aRegionToClear,
+                                     uint64_t aId,
+                                     bool aScheduleComposite,
+                                     uint32_t aPaintSequenceNumber,
+                                     bool aIsRepeatTransaction,
+                                     const mozilla::TimeStamp& aTransactionStart,
+                                     bool* aSent)
+{
+  *aSent = false;
+
+  MOZ_ASSERT(IPCOpen(), "no manager to forward to");
+  if (!IPCOpen()) {
+    return false;
+  }
+
+  GetCompositorBridgeChild()->WillEndTransaction();
+
+  MOZ_ASSERT(aId);
+
+  PROFILER_LABEL("ShadowLayerForwarder", "EndTransaction",
+    js::ProfileEntry::Category::GRAPHICS);
+
+  RenderTraceScope rendertrace("Foward Transaction", "000091");
+  MOZ_ASSERT(!mTxn->Finished(), "forgot BeginTransaction?");
+
+  DiagnosticTypes diagnostics = gfxPlatform::GetPlatform()->GetLayerDiagnosticTypes();
+  if (mDiagnosticTypes != diagnostics) {
+    mDiagnosticTypes = diagnostics;
+    mTxn->AddEdit(OpSetDiagnosticTypes(diagnostics));
+  }
+  if (mWindowOverlayChanged) {
+    mTxn->AddEdit(OpWindowOverlayChanged());
+  }
+
+  AutoTxnEnd _(mTxn);
+
+  if (mTxn->Empty() && !mTxn->RotationChanged()) {
+    MOZ_LAYERS_LOG(("[LayersForwarder] 0-length cset (?) and no rotation event, skipping Update()"));
+    return true;
+  }
+
+  if (!mTxn->mPaints.empty()) {
+    // With some platforms, telling the drawing backend that there will be no more
+    // drawing for this frame helps with preventing command queues from spanning
+    // across multiple frames.
+    gfxPlatform::GetPlatform()->FlushContentDrawing();
+  }
+
+  MOZ_LAYERS_LOG(("[LayersForwarder] destroying buffers..."));
+
+  MOZ_LAYERS_LOG(("[LayersForwarder] building transaction..."));
+
+  // We purposely add attribute-change ops to the final changeset
+  // before we add paint ops.  This allows layers to record the
+  // attribute changes before new pixels arrive, which can be useful
+  // for setting up back/front buffers.
+  RenderTraceScope rendertrace2("Foward Transaction", "000092");
+  for (ShadowableLayerSet::Iterator it(&mTxn->mMutants);
+       !it.Done(); it.Next()) {
+    ShadowableLayer* shadow = it.Get()->GetKey();
+
+    if (!shadow->HasShadow()) {
+      continue;
+    }
+    Layer* mutant = shadow->AsLayer();
+    MOZ_ASSERT(!!mutant, "unshadowable layer?");
+
+    LayerAttributes attrs;
+    CommonLayerAttributes& common = attrs.common();
+    common.layerBounds() = mutant->GetLayerBounds();
+    common.visibleRegion() = mutant->GetVisibleRegion();
+    common.eventRegions() = mutant->GetEventRegions();
+    common.postXScale() = mutant->GetPostXScale();
+    common.postYScale() = mutant->GetPostYScale();
+    common.transform() = mutant->GetBaseTransform();
+    common.transformIsPerspective() = mutant->GetTransformIsPerspective();
+    common.contentFlags() = mutant->GetContentFlags();
+    common.opacity() = mutant->GetOpacity();
+    common.useClipRect() = !!mutant->GetClipRect();
+    common.clipRect() = (common.useClipRect() ?
+                         *mutant->GetClipRect() : ParentLayerIntRect());
+    common.scrolledClip() = mutant->GetScrolledClip();
+    common.isFixedPosition() = mutant->GetIsFixedPosition();
+    if (mutant->GetIsFixedPosition()) {
+      common.fixedPositionScrollContainerId() = mutant->GetFixedPositionScrollContainerId();
+      common.fixedPositionAnchor() = mutant->GetFixedPositionAnchor();
+      common.fixedPositionSides() = mutant->GetFixedPositionSides();
+    }
+    common.isStickyPosition() = mutant->GetIsStickyPosition();
+    if (mutant->GetIsStickyPosition()) {
+      common.stickyScrollContainerId() = mutant->GetStickyScrollContainerId();
+      common.stickyScrollRangeOuter() = mutant->GetStickyScrollRangeOuter();
+      common.stickyScrollRangeInner() = mutant->GetStickyScrollRangeInner();
+    } else {
+#ifdef MOZ_VALGRIND
+      // Initialize these so that Valgrind doesn't complain when we send them
+      // to another process.
+      common.stickyScrollContainerId() = 0;
+      common.stickyScrollRangeOuter() = LayerRect();
+      common.stickyScrollRangeInner() = LayerRect();
+#endif
+    }
+    common.scrollbarTargetContainerId() = mutant->GetScrollbarTargetContainerId();
+    common.scrollbarDirection() = mutant->GetScrollbarDirection();
+    common.scrollbarThumbRatio() = mutant->GetScrollbarThumbRatio();
+    common.isScrollbarContainer() = mutant->IsScrollbarContainer();
+    common.mixBlendMode() = (int8_t)mutant->GetMixBlendMode();
+    common.forceIsolatedGroup() = mutant->GetForceIsolatedGroup();
+    if (Layer* maskLayer = mutant->GetMaskLayer()) {
+      common.maskLayerChild() = Shadow(maskLayer->AsShadowableLayer());
+    } else {
+      common.maskLayerChild() = nullptr;
+    }
+    common.maskLayerParent() = nullptr;
+    common.animations() = mutant->GetAnimations();
+    common.invalidRegion() = mutant->GetInvalidRegion().GetRegion();
+    common.scrollMetadata() = mutant->GetAllScrollMetadata();
+    for (size_t i = 0; i < mutant->GetAncestorMaskLayerCount(); i++) {
+      auto layer = Shadow(mutant->GetAncestorMaskLayerAt(i)->AsShadowableLayer());
+      common.ancestorMaskLayersChild().AppendElement(layer);
+    }
+    nsCString log;
+    mutant->GetDisplayListLog(log);
+    common.displayListLog() = log;
+
+    attrs.specific() = null_t();
+    mutant->FillSpecificAttributes(attrs.specific());
+
+    MOZ_LAYERS_LOG(("[LayersForwarder] OpSetLayerAttributes(%p)\n", mutant));
+
+    mTxn->AddEdit(OpSetLayerAttributes(nullptr, Shadow(shadow), attrs));
+  }
+
+  AutoTArray<Edit, 10> cset;
+  size_t nCsets = mTxn->mCset.size() + mTxn->mPaints.size();
+  if (nCsets == 0 && !mTxn->RotationChanged()) {
+    return true;
+  }
+
+  cset.SetCapacity(nCsets);
+  if (!mTxn->mCset.empty()) {
+    cset.AppendElements(&mTxn->mCset.front(), mTxn->mCset.size());
+  }
+  // Paints after non-paint ops, including attribute changes.  See
+  // above.
+  if (!mTxn->mPaints.empty()) {
+    cset.AppendElements(&mTxn->mPaints.front(), mTxn->mPaints.size());
+  }
+
+  mWindowOverlayChanged = false;
+
+  TargetConfig targetConfig(mTxn->mTargetBounds,
+                            mTxn->mTargetRotation,
+                            mTxn->mTargetOrientation,
+                            aRegionToClear);
+
+  if (!GetTextureForwarder()->IsSameProcess()) {
+    MOZ_LAYERS_LOG(("[LayersForwarder] syncing before send..."));
+    PlatformSyncBeforeUpdate();
+  }
+
+  profiler_tracing("Paint", "Rasterize", TRACING_INTERVAL_END);
+  if (mTxn->mSwapRequired) {
+    MOZ_LAYERS_LOG(("[LayersForwarder] sending transaction..."));
+    RenderTraceScope rendertrace3("Forward Transaction", "000093");
+    if (!mShadowManager->SendUpdate(cset, mTxn->mDestroyedActors,
+                                    GetFwdTransactionId(),
+                                    aId, targetConfig, mPluginWindowData,
+                                    mIsFirstPaint, aScheduleComposite,
+                                    aPaintSequenceNumber, aIsRepeatTransaction,
+                                    aTransactionStart, mPaintSyncId, aReplies)) {
+      MOZ_LAYERS_LOG(("[LayersForwarder] WARNING: sending transaction failed!"));
+      return false;
+    }
+  } else {
+    // If we don't require a swap we can call SendUpdateNoSwap which
+    // assumes that aReplies is empty (DEBUG assertion)
+    MOZ_LAYERS_LOG(("[LayersForwarder] sending no swap transaction..."));
+    RenderTraceScope rendertrace3("Forward NoSwap Transaction", "000093");
+    if (!mShadowManager->SendUpdateNoSwap(cset, mTxn->mDestroyedActors,
+                                          GetFwdTransactionId(),
+                                          aId, targetConfig, mPluginWindowData,
+                                          mIsFirstPaint, aScheduleComposite,
+                                          aPaintSequenceNumber, aIsRepeatTransaction,
+                                          aTransactionStart, mPaintSyncId)) {
+      MOZ_LAYERS_LOG(("[LayersForwarder] WARNING: sending transaction failed!"));
+      return false;
+    }
+  }
+
+  *aSent = true;
+  mIsFirstPaint = false;
+  mPaintSyncId = 0;
+  MOZ_LAYERS_LOG(("[LayersForwarder] ... done"));
+  return true;
+}
+
+void
+ShadowLayerForwarder::SetLayerObserverEpoch(uint64_t aLayerObserverEpoch)
+{
+  if (!IPCOpen()) {
+    return;
+  }
+  Unused << mShadowManager->SendSetLayerObserverEpoch(aLayerObserverEpoch);
+}
+
+bool
+ShadowLayerForwarder::IPCOpen() const
+{
+  return HasShadowManager() && mShadowManager->IPCOpen();
+}
+
+/**
+  * We bail out when we have no shadow manager. That can happen when the
+  * layer manager is created by the preallocated process.
+  * See bug 914843 for details.
+  */
+PLayerChild*
+ShadowLayerForwarder::ConstructShadowFor(ShadowableLayer* aLayer)
+{
+  MOZ_ASSERT(IPCOpen(), "no manager to forward to");
+  if (!IPCOpen()) {
+    return nullptr;
+  }
+
+  ShadowLayerChild* child = new ShadowLayerChild();
+  if (!mShadowManager->SendPLayerConstructor(child)) {
+    return nullptr;
+  }
+
+  child->SetShadowableLayer(aLayer);
+  return child;
+}
+
+#if !defined(MOZ_HAVE_PLATFORM_SPECIFIC_LAYER_BUFFERS)
+
+/*static*/ void
+ShadowLayerForwarder::PlatformSyncBeforeUpdate()
+{
+}
+
+#endif  // !defined(MOZ_HAVE_PLATFORM_SPECIFIC_LAYER_BUFFERS)
+
+void
+ShadowLayerForwarder::Connect(CompositableClient* aCompositable,
+                              ImageContainer* aImageContainer)
+{
+#ifdef GFX_COMPOSITOR_LOGGING
+  printf("ShadowLayerForwarder::Connect(Compositable)\n");
+#endif
+  MOZ_ASSERT(aCompositable);
+  MOZ_ASSERT(mShadowManager);
+  if (!IPCOpen()) {
+    return;
+  }
+  PCompositableChild* actor =
+    mShadowManager->SendPCompositableConstructor(aCompositable->GetTextureInfo());
+  if (!actor) {
+    return;
+  }
+  aCompositable->InitIPDLActor(actor);
+}
+
+void ShadowLayerForwarder::Attach(CompositableClient* aCompositable,
+                                  ShadowableLayer* aLayer)
+{
+  MOZ_ASSERT(aLayer);
+  MOZ_ASSERT(aCompositable);
+  mTxn->AddEdit(OpAttachCompositable(nullptr, Shadow(aLayer),
+                                     nullptr, aCompositable->GetIPDLActor()));
+}
+
+void ShadowLayerForwarder::AttachAsyncCompositable(uint64_t aCompositableID,
+                                                   ShadowableLayer* aLayer)
+{
+  MOZ_ASSERT(aLayer);
+  MOZ_ASSERT(aCompositableID != 0); // zero is always an invalid compositable id.
+  mTxn->AddEdit(OpAttachAsyncCompositable(nullptr, Shadow(aLayer),
+                                          aCompositableID));
+}
+
+void ShadowLayerForwarder::SetShadowManager(PLayerTransactionChild* aShadowManager)
+{
+  mShadowManager = static_cast<LayerTransactionChild*>(aShadowManager);
+  mShadowManager->SetForwarder(this);
+}
+
+void ShadowLayerForwarder::StopReceiveAsyncParentMessge()
+{
+  if (!IPCOpen()) {
+    return;
+  }
+  mShadowManager->SetForwarder(nullptr);
+}
+
+void ShadowLayerForwarder::ClearCachedResources()
+{
+  if (!IPCOpen()) {
+    return;
+  }
+  mShadowManager->SendClearCachedResources();
+}
+
+void ShadowLayerForwarder::Composite()
+{
+  if (!IPCOpen()) {
+    return;
+  }
+  mShadowManager->SendForceComposite();
+}
+
+bool
+IsSurfaceDescriptorValid(const SurfaceDescriptor& aSurface)
+{
+  return aSurface.type() != SurfaceDescriptor::T__None &&
+         aSurface.type() != SurfaceDescriptor::Tnull_t;
+}
+
+uint8_t*
+GetAddressFromDescriptor(const SurfaceDescriptor& aDescriptor)
+{
+  MOZ_ASSERT(IsSurfaceDescriptorValid(aDescriptor));
+  MOZ_RELEASE_ASSERT(aDescriptor.type() == SurfaceDescriptor::TSurfaceDescriptorBuffer, "GFX: surface descriptor is not the right type.");
+
+  auto memOrShmem = aDescriptor.get_SurfaceDescriptorBuffer().data();
+  if (memOrShmem.type() == MemoryOrShmem::TShmem) {
+    return memOrShmem.get_Shmem().get<uint8_t>();
+  } else {
+    return reinterpret_cast<uint8_t*>(memOrShmem.get_uintptr_t());
+  }
+}
+
+already_AddRefed<gfx::DataSourceSurface>
+GetSurfaceForDescriptor(const SurfaceDescriptor& aDescriptor)
+{
+  if (aDescriptor.type() != SurfaceDescriptor::TSurfaceDescriptorBuffer) {
+    return nullptr;
+  }
+  uint8_t* data = GetAddressFromDescriptor(aDescriptor);
+  auto rgb = aDescriptor.get_SurfaceDescriptorBuffer().desc().get_RGBDescriptor();
+  uint32_t stride = ImageDataSerializer::GetRGBStride(rgb);
+  return gfx::Factory::CreateWrappingDataSourceSurface(data, stride, rgb.size(),
+                                                       rgb.format());
+}
+
+already_AddRefed<gfx::DrawTarget>
+GetDrawTargetForDescriptor(const SurfaceDescriptor& aDescriptor, gfx::BackendType aBackend)
+{
+  uint8_t* data = GetAddressFromDescriptor(aDescriptor);
+  auto rgb = aDescriptor.get_SurfaceDescriptorBuffer().desc().get_RGBDescriptor();
+  uint32_t stride = ImageDataSerializer::GetRGBStride(rgb);
+  return gfx::Factory::CreateDrawTargetForData(gfx::BackendType::CAIRO,
+                                               data, rgb.size(),
+                                               stride, rgb.format());
+}
+
+void
+DestroySurfaceDescriptor(IShmemAllocator* aAllocator, SurfaceDescriptor* aSurface)
+{
+  MOZ_ASSERT(aSurface);
+
+  SurfaceDescriptorBuffer& desc = aSurface->get_SurfaceDescriptorBuffer();
+  switch (desc.data().type()) {
+    case MemoryOrShmem::TShmem: {
+      aAllocator->DeallocShmem(desc.data().get_Shmem());
+      break;
+    }
+    case MemoryOrShmem::Tuintptr_t: {
+      uint8_t* ptr = (uint8_t*)desc.data().get_uintptr_t();
+      GfxMemoryImageReporter::WillFree(ptr);
+      delete [] ptr;
+      break;
+    }
+    default:
+      NS_RUNTIMEABORT("surface type not implemented!");
+  }
+  *aSurface = SurfaceDescriptor();
+}
+
+bool
+ShadowLayerForwarder::AllocSurfaceDescriptor(const gfx::IntSize& aSize,
+                                             gfxContentType aContent,
+                                             SurfaceDescriptor* aBuffer)
+{
+  if (!IPCOpen()) {
+    return false;
+  }
+  return AllocSurfaceDescriptorWithCaps(aSize, aContent, DEFAULT_BUFFER_CAPS, aBuffer);
+}
+
+bool
+ShadowLayerForwarder::AllocSurfaceDescriptorWithCaps(const gfx::IntSize& aSize,
+                                                     gfxContentType aContent,
+                                                     uint32_t aCaps,
+                                                     SurfaceDescriptor* aBuffer)
+{
+  if (!IPCOpen()) {
+    return false;
+  }
+  gfx::SurfaceFormat format =
+    gfxPlatform::GetPlatform()->Optimal2DFormatForContent(aContent);
+  size_t size = ImageDataSerializer::ComputeRGBBufferSize(aSize, format);
+  if (!size) {
+    return false;
+  }
+
+  MemoryOrShmem bufferDesc;
+  if (GetTextureForwarder()->IsSameProcess()) {
+    uint8_t* data = new (std::nothrow) uint8_t[size];
+    if (!data) {
+      return false;
+    }
+    GfxMemoryImageReporter::DidAlloc(data);
+    memset(data, 0, size);
+    bufferDesc = reinterpret_cast<uintptr_t>(data);
+  } else {
+
+    mozilla::ipc::Shmem shmem;
+    if (!GetTextureForwarder()->AllocUnsafeShmem(size, OptimalShmemType(), &shmem)) {
+      return false;
+    }
+
+    bufferDesc = shmem;
+  }
+
+  // Use an intermediate buffer by default. Skipping the intermediate buffer is
+  // only possible in certain configurations so let's keep it simple here for now.
+  const bool hasIntermediateBuffer = true;
+  *aBuffer = SurfaceDescriptorBuffer(RGBDescriptor(aSize, format, hasIntermediateBuffer),
+                                     bufferDesc);
+
+  return true;
+}
+
+/* static */ bool
+ShadowLayerForwarder::IsShmem(SurfaceDescriptor* aSurface)
+{
+  return aSurface && (aSurface->type() == SurfaceDescriptor::TSurfaceDescriptorBuffer)
+      && (aSurface->get_SurfaceDescriptorBuffer().data().type() == MemoryOrShmem::TShmem);
+}
+
+void
+ShadowLayerForwarder::DestroySurfaceDescriptor(SurfaceDescriptor* aSurface)
+{
+  MOZ_ASSERT(aSurface);
+  MOZ_ASSERT(IPCOpen());
+  if (!IPCOpen() || !aSurface) {
+    return;
+  }
+
+  ::mozilla::layers::DestroySurfaceDescriptor(GetTextureForwarder(), aSurface);
+}
+
+void
+ShadowLayerForwarder::UpdateFwdTransactionId()
+{
+  auto compositorBridge = GetCompositorBridgeChild();
+  if (compositorBridge) {
+    compositorBridge->UpdateFwdTransactionId();
+  }
+}
+
+uint64_t
+ShadowLayerForwarder::GetFwdTransactionId()
+{
+  auto compositorBridge = GetCompositorBridgeChild();
+  MOZ_DIAGNOSTIC_ASSERT(compositorBridge);
+  return compositorBridge ? compositorBridge->GetFwdTransactionId() : 0;
+}
+
+CompositorBridgeChild*
+ShadowLayerForwarder::GetCompositorBridgeChild()
+{
+  if (mCompositorBridgeChild) {
+    return mCompositorBridgeChild;
+  }
+  if (!mShadowManager) {
+    return nullptr;
+  }
+  mCompositorBridgeChild = static_cast<CompositorBridgeChild*>(mShadowManager->Manager());
+  return mCompositorBridgeChild;
+}
+
+} // namespace layers
+} // namespace mozilla