Bug 1508484 - close audio queue if we already got the last audio frame when leaving 'loopingDecoding' state r=jya

When we're going to leave looping state and have got EOS before, we should mark audio queue
as ended because we have got all data we need.

Differential Revision: https://phabricator.services.mozilla.com/D12373

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

dom/media/MediaDecoderStateMachine.cpp

@@ -762,8 +762,12 @@ class MediaDecoderStateMachine::LoopingDecodingState
     if (ShouldDiscardLoopedAudioData()) {
       mMaster->mAudioDataRequest.DisconnectIfExists();
       DiscardLoopedAudioData();
+    }
+    if (HasDecodedLastAudioFrame()) {
       AudioQueue().Finish();
     }
+    mAudioDataRequest.DisconnectIfExists();
+    mAudioSeekRequest.DisconnectIfExists();
     DecodingState::Exit();
   }
 
@@ -890,6 +894,14 @@ class MediaDecoderStateMachine::LoopingDecodingState
     });
   }
 
+  bool HasDecodedLastAudioFrame() const {
+    // when we're going to leave looping state and have got EOS before, we should
+    // mark audio queue as ended because we have got all data we need.
+    return mAudioDataRequest.Exists() ||
+           mAudioSeekRequest.Exists() ||
+           ShouldDiscardLoopedAudioData();
+  }
+
   media::TimeUnit mAudioLoopingOffset = media::TimeUnit::Zero();
   MozPromiseRequestHolder<MediaFormatReader::SeekPromise> mAudioSeekRequest;
   MozPromiseRequestHolder<AudioDataPromise> mAudioDataRequest;