Bug 1423241 - Ignore runnables for main thread after next stream state update, after entering shutdown. r=padenot

They may hang on to references causing leaks.

Differential Revision: https://phabricator.services.mozilla.com/D12281

--HG--
extra : moz-landing-system : lando

dom/media/MediaStreamGraph.cpp

@@ -1562,6 +1562,9 @@ class MediaStreamGraphShutDownRunnable : public Runnable {
       stream->RemoveAllListenersImpl();
     }
 
+    MOZ_ASSERT(mGraph->mUpdateRunnables.IsEmpty());
+    mGraph->mPendingUpdateRunnables.Clear();
+
     mGraph->mForceShutdownTicket = nullptr;
 
     // We can't block past the final LIFECYCLE_WAITING_FOR_STREAM_DESTRUCTION
@@ -4004,7 +4007,8 @@ already_AddRefed<MediaInputPort> MediaStreamGraphImpl::ConnectToCaptureStream(
 void MediaStreamGraph::DispatchToMainThreadAfterStreamStateUpdate(
     already_AddRefed<nsIRunnable> aRunnable) {
   AssertOnGraphThreadOrNotRunning();
-  *mPendingUpdateRunnables.AppendElement() =
+  *static_cast<MediaStreamGraphImpl*>(this)
+       ->mPendingUpdateRunnables.AppendElement() =
       AbstractMainThread()->CreateDirectTaskDrainer(std::move(aRunnable));
 }
 

dom/media/MediaStreamGraph.h

@@ -1324,8 +1324,11 @@ class MediaStreamGraph {
    *
    * Should only be called during MediaStreamListener callbacks or during
    * ProcessedMediaStream::ProcessInput().
+   *
+   * Note that if called during shutdown the runnable will be ignored and
+   * released on main thread.
    */
-  virtual void DispatchToMainThreadAfterStreamStateUpdate(
+  void DispatchToMainThreadAfterStreamStateUpdate(
       already_AddRefed<nsIRunnable> aRunnable);
 
   /**
@@ -1360,9 +1363,6 @@ class MediaStreamGraph {
   bool OnGraphThreadOrNotRunning() const;
   bool OnGraphThread() const;
 
-  // Media graph thread only
-  nsTArray<nsCOMPtr<nsIRunnable>> mPendingUpdateRunnables;
-
   /**
    * Sample rate at which this graph runs. For real time graphs, this is
    * the rate of the audio mixer. For offline graphs, this is the rate specified

dom/media/MediaStreamGraphImpl.h

@@ -652,6 +652,11 @@ class MediaStreamGraphImpl : public MediaStreamGraph,
    * Number of active MediaInputPorts
    */
   int32_t mPortCount;
+  /**
+   * Runnables to run after the next update to main thread state, but that are
+   * still waiting for the next iteration to finish.
+   */
+  nsTArray<nsCOMPtr<nsIRunnable>> mPendingUpdateRunnables;
 
   /**
    * Devices to use for cubeb input & output, or nullptr for default device.