Re-land "Dispatch AudioSink notifications asynchronously"

Turns out that this is needed after all.

dom/media/AudioSink.cpp

@@ -202,7 +202,7 @@ AudioSink::AudioLoop()
     }
     int64_t endTime = GetEndTime();
     if (endTime != -1) {
-      mStateMachine->OnAudioEndTimeUpdate(endTime);
+      mStateMachine->DispatchOnAudioEndTimeUpdate(endTime);
     }
   }
   ReentrantMonitorAutoEnter mon(GetReentrantMonitor());
@@ -256,7 +256,7 @@ AudioSink::Cleanup()
   AssertCurrentThreadInMonitor();
   nsRefPtr<AudioStream> audioStream;
   audioStream.swap(mAudioStream);
-  mStateMachine->OnAudioSinkComplete();
+  mStateMachine->DispatchOnAudioSinkComplete();
 
   ReentrantMonitorAutoExit exit(GetReentrantMonitor());
   audioStream->Shutdown();
@@ -340,7 +340,7 @@ AudioSink::PlayFromAudioQueue()
   StartAudioStreamPlaybackIfNeeded();
 
   if (audio->mOffset != -1) {
-    mStateMachine->OnPlaybackOffsetUpdate(audio->mOffset);
+    mStateMachine->DispatchOnPlaybackOffsetUpdate(audio->mOffset);
   }
   return audio->mFrames;
 }

dom/media/MediaDecoder.cpp

@@ -1535,7 +1535,7 @@ void MediaDecoder::SetLoadInBackground(bool aLoadInBackground)
 
 void MediaDecoder::UpdatePlaybackOffset(int64_t aOffset)
 {
-  ReentrantMonitorAutoEnter mon(GetReentrantMonitor());
+  GetReentrantMonitor().AssertCurrentThreadIn();
   mPlaybackPosition = aOffset;
 }
 

dom/media/MediaDecoderStateMachine.cpp

@@ -3417,6 +3417,7 @@ void MediaDecoderStateMachine::QueueMetadata(int64_t aPublishTime,
 
 void MediaDecoderStateMachine::OnAudioEndTimeUpdate(int64_t aAudioEndTime)
 {
+  MOZ_ASSERT(OnTaskQueue());
   ReentrantMonitorAutoEnter mon(mDecoder->GetReentrantMonitor());
   MOZ_ASSERT(aAudioEndTime >= mAudioEndTime);
   mAudioEndTime = aAudioEndTime;
@@ -3424,11 +3425,15 @@ void MediaDecoderStateMachine::OnAudioEndTimeUpdate(int64_t aAudioEndTime)
 
 void MediaDecoderStateMachine::OnPlaybackOffsetUpdate(int64_t aPlaybackOffset)
 {
+  MOZ_ASSERT(OnTaskQueue());
+  ReentrantMonitorAutoEnter mon(mDecoder->GetReentrantMonitor());
   mDecoder->UpdatePlaybackOffset(aPlaybackOffset);
 }
 
 void MediaDecoderStateMachine::OnAudioSinkComplete()
 {
+  MOZ_ASSERT(OnTaskQueue());
+  ReentrantMonitorAutoEnter mon(mDecoder->GetReentrantMonitor());
   if (mAudioCaptured) {
     return;
   }

dom/media/MediaDecoderStateMachine.h

@@ -728,15 +728,37 @@ protected:
   // Can only be called on the state machine thread.
   void SetPlayStartTime(const TimeStamp& aTimeStamp);
 
+private:
   // Update mAudioEndTime.
   void OnAudioEndTimeUpdate(int64_t aAudioEndTime);
+public:
+  void DispatchOnAudioEndTimeUpdate(int64_t aAudioEndTime)
+  {
+    RefPtr<nsRunnable> r =
+      NS_NewRunnableMethodWithArg<int64_t>(this, &MediaDecoderStateMachine::OnAudioEndTimeUpdate, aAudioEndTime);
+    TaskQueue()->Dispatch(r.forget());
+  }
 
+private:
   // Update mDecoder's playback offset.
   void OnPlaybackOffsetUpdate(int64_t aPlaybackOffset);
+public:
+  void DispatchOnPlaybackOffsetUpdate(int64_t aPlaybackOffset)
+  {
+    RefPtr<nsRunnable> r =
+      NS_NewRunnableMethodWithArg<int64_t>(this, &MediaDecoderStateMachine::OnPlaybackOffsetUpdate, aPlaybackOffset);
+    TaskQueue()->Dispatch(r.forget());
+  }
 
+private:
   // Called by the AudioSink to signal that all outstanding work is complete
   // and the sink is shutting down.
   void OnAudioSinkComplete();
+public:
+  void DispatchOnAudioSinkComplete()
+  {
+    TaskQueue()->Dispatch(NS_NewRunnableMethod(this, &MediaDecoderStateMachine::OnAudioSinkComplete));
+  }
 
   // Called by the AudioSink to signal errors.
   void OnAudioSinkError();