Bug 1453127 - Clear output streams on shutdown. r=jya

dom/media/MediaDecoderStateMachine.cpp

@@ -3448,6 +3448,10 @@ MediaDecoderStateMachine::FinishDecodeFirstFrame()
 RefPtr<ShutdownPromise>
 MediaDecoderStateMachine::BeginShutdown()
 {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mOutputStreamManager) {
+    mOutputStreamManager->Clear();
+  }
   return InvokeAsync(OwnerThread(), this, __func__,
                      &MediaDecoderStateMachine::Shutdown);
 }

dom/media/mediasink/OutputStreamManager.cpp

@@ -125,6 +125,13 @@ OutputStreamManager::Remove(MediaStream* aStream)
   }
 }
 
+void
+OutputStreamManager::Clear()
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  mStreams.Clear();
+}
+
 TrackID
 OutputStreamManager::NextAvailableTrackIDFor(MediaStream* aOutputStream) const
 {

dom/media/mediasink/OutputStreamManager.h

@@ -59,6 +59,8 @@ public:
            bool aFinishWhenEnded);
   // Remove the output stream from the collection.
   void Remove(MediaStream* aStream);
+  // Clear all output streams from the collection.
+  void Clear();
   // The next TrackID that will not cause a collision in aOutputStream.
   TrackID NextAvailableTrackIDFor(MediaStream* aOutputStream) const;
   // Return true if the collection empty.