Bug 1306551 - don't update playback position for video-only seek when seek is completed. r=kaku

MozReview-Commit-ID: 7vByX0pPNo

--HG--
extra : rebase_source : e8a818eb38c37c41060ec03ce6d31357bb15c218
extra : source : b0732e355e045fc859e740a996d98c54f5b8a61e

dom/media/MediaDecoderStateMachine.cpp

@@ -963,7 +963,12 @@ private:
     }
 
     // Ensure timestamps are up to date.
+    if (!mSeekJob.mTarget.IsVideoOnly()) {
+      // Don't update playback position for video-only seek.
+      // Otherwise we might have |newCurrentTime > mMediaSink->GetPosition()|
+      // and fail the assertion in GetClock() since we didn't stop MediaSink.
       mMaster->UpdatePlaybackPositionInternal(newCurrentTime);
+    }
 
     // Try to decode another frame to detect if we're at the end...
     SLOG("Seek completed, mCurrentPosition=%lld", mMaster->mCurrentPosition.Ref());