From 9830cd079d8306abc223461190553af64b6fd0ca Mon Sep 17 00:00:00 2001
From: wolfbeast <mcwerewolf@gmail.com>
Date: Tue, 11 Sep 2018 14:48:21 +0200
Subject: Bug 1472925 - Keep a strong reference to MediaStreamGraph from
 GraphDriver.

---
 dom/media/GraphDriver.cpp      | 8 +++++---
 dom/media/GraphDriver.h        | 6 ++----
 dom/media/MediaStreamGraph.cpp | 3 ++-
 3 files changed, 9 insertions(+), 8 deletions(-)

(limited to 'dom/media')

diff --git a/dom/media/GraphDriver.cpp b/dom/media/GraphDriver.cpp
index cae15eb8c..e77268131 100644
--- a/dom/media/GraphDriver.cpp
+++ b/dom/media/GraphDriver.cpp
@@ -200,7 +200,7 @@ public:
     STREAM_LOG(LogLevel::Debug, ("Starting system thread"));
     profiler_register_thread("MediaStreamGraph", &aLocal);
     LIFECYCLE_LOG("Starting a new system driver for graph %p\n",
-                  mDriver->mGraphImpl);
+                  mDriver->mGraphImpl.get());
 
     RefPtr<GraphDriver> previousDriver;
     {
@@ -236,7 +236,7 @@ private:
 void
 ThreadedDriver::Start()
 {
-  LIFECYCLE_LOG("Starting thread for a SystemClockDriver  %p\n", mGraphImpl);
+  LIFECYCLE_LOG("Starting thread for a SystemClockDriver  %p\n", mGraphImpl.get());
   Unused << NS_WARN_IF(mThread);
   if (!mThread) { // Ensure we haven't already started it
     nsCOMPtr<nsIRunnable> event = new MediaStreamGraphInitThreadRunnable(this);
@@ -830,7 +830,9 @@ AudioCallbackDriver::Revive()
     mGraphImpl->SetCurrentDriver(NextDriver());
     NextDriver()->Start();
   } else {
-    STREAM_LOG(LogLevel::Debug, ("Starting audio threads for MediaStreamGraph %p from a new thread.", mGraphImpl));
+    STREAM_LOG(LogLevel::Debug,
+               ("Starting audio threads for MediaStreamGraph %p from a new thread.",
+                mGraphImpl.get()));
     RefPtr<AsyncCubebTask> initEvent =
       new AsyncCubebTask(this, AsyncCubebOperation::INIT);
     initEvent->Dispatch();
diff --git a/dom/media/GraphDriver.h b/dom/media/GraphDriver.h
index 411e175d3..bb4f2689b 100644
--- a/dom/media/GraphDriver.h
+++ b/dom/media/GraphDriver.h
@@ -210,10 +210,8 @@ protected:
   // Time of the end of this graph iteration. This must be accessed while having
   // the monitor.
   GraphTime mIterationEnd;
-  // The MediaStreamGraphImpl that owns this driver. This has a lifetime longer
-  // than the driver, and will never be null. Hence, it can be accesed without
-  // monitor.
-  MediaStreamGraphImpl* mGraphImpl;
+  // The MediaStreamGraphImpl associated with this driver.
+  const RefPtr<MediaStreamGraphImpl> mGraphImpl;
 
   // This enum specifies the wait state of the driver.
   enum WaitState {
diff --git a/dom/media/MediaStreamGraph.cpp b/dom/media/MediaStreamGraph.cpp
index e2934cbb2..1b9e4f674 100644
--- a/dom/media/MediaStreamGraph.cpp
+++ b/dom/media/MediaStreamGraph.cpp
@@ -3371,7 +3371,8 @@ MediaStreamGraphImpl::Destroy()
   // First unregister from memory reporting.
   UnregisterWeakMemoryReporter(this);
 
-  // Clear the self reference which will destroy this instance.
+  // Clear the self reference which will destroy this instance if all
+  // associated GraphDrivers are destroyed.
   mSelfRef = nullptr;
 }
 
-- 
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