import changes from `dev' branch of rmottola/Arctic-Fox:

- Bug 1246051 - have MediaQueue<T>::Peek/PeekFront return a RefPtr<> to avoid dangling pointers per comment 0. r=gerald. (00f334efb1)
- Bug 1264199: P1. Perform audio conversion in the MSDM taskqueue and ahead of use. r=kinetik (001936e3ea)
- Bug 1267983 - include MediaQueue.h; r=jwwang (036107d765)
- Bug 1264199: P0. Fix nsDequeue/MediaQueue methods constness. r=jwwang (9aa33dfcb5)
- Bug 1264199: P0.1. Export SaferMultDiv method. r=gerald (0b7a35ae4d)
- Bug 1264199: P2. Ensure the AudioStream only ever receive the same content format. r=kinetik (a180d09279)
- Bug 1264199: P3. Attempt to minimize audio quality loss and unnecessary processing. r=kinetik (29d57b5a33)
- Bug 1264199: P4. Add mono to stereo upmix to AudioConverter. r=rillian (49c029bd86)
- Bug 1264199: P5. Perform all downmixing operations in DecodedAudioDataSink. r=kinetik (05a479f095)
- Bug 1264199: P6. Drain resampler when changing format or reaching the end. r=kinetik (8639102a94)
- Bug 1264199: P8. Handle potential resampling errors. r=kinetik (1267e4e73d)
- Bug 1264199: P9. Include pending frames in HasUnplayedFrames calculation. r=jwwang (ce7097fc90)

dom/media/MediaDecoderStateMachine.cpp

@@ -364,7 +364,7 @@ MediaDecoderStateMachine::CreateAudioSink()
   auto audioSinkCreator = [self] () {
     MOZ_ASSERT(self->OnTaskQueue());
     return new DecodedAudioDataSink(
-      self->mAudioQueue, self->GetMediaTime(),
+      self->mTaskQueue, self->mAudioQueue, self->GetMediaTime(),
       self->mInfo.mAudio, self->mAudioChannel);
   };
   return new AudioSinkWrapper(mTaskQueue, audioSinkCreator);
@@ -428,7 +428,7 @@ void MediaDecoderStateMachine::DiscardStreamData()
 
   const auto clockTime = GetClock();
   while (true) {
-    const MediaData* a = AudioQueue().PeekFront();
+    RefPtr<MediaData> a = AudioQueue().PeekFront();
 
     // If we discard audio samples fed to the stream immediately, we will
     // keep decoding audio samples till the end and consume a lot of memory.
@@ -1983,7 +1983,7 @@ MediaDecoderStateMachine::SeekCompleted()
   if (seekTime == Duration().ToMicroseconds()) {
     newCurrentTime = seekTime;
   } else if (HasAudio()) {
-    MediaData* audio = AudioQueue().PeekFront();
+    RefPtr<MediaData> audio = AudioQueue().PeekFront();
     // Though we adjust the newCurrentTime in audio-based, and supplemented
     // by video. For better UX, should NOT bind the slide position to
     // the first audio data timestamp directly.