Allow media track switching.

media/renderers/renderer_impl.h

Index: media/renderers/renderer_impl.h
diff --git a/media/renderers/renderer_impl.h b/media/renderers/renderer_impl.h
index f55a7635e22707644c5b818813542d23a49544c0..1a5849746bb8ad363321edd195c938d7425e61e3 100644
--- a/media/renderers/renderer_impl.h
+++ b/media/renderers/renderer_impl.h
@@ -61,10 +61,6 @@ class MEDIA_EXPORT RendererImpl : public Renderer {
   void SetVolume(float volume) final;
   base::TimeDelta GetMediaTime() final;
 
-  void OnStreamStatusChanged(DemuxerStream* stream,
-                             bool enabled,
-                             base::TimeDelta time);
-
   // Helper functions for testing purposes. Must be called before Initialize().
   void DisableUnderflowForTesting();
   void EnableClocklessVideoPlaybackForTesting();
@@ -106,8 +102,36 @@ class MEDIA_EXPORT RendererImpl : public Renderer {
   void FlushVideoRenderer();
   void OnVideoRendererFlushDone();
 
-  void RestartAudioRenderer(base::TimeDelta time);
-  void RestartVideoRenderer(base::TimeDelta time);
+  // This function notifies the renderer that the status of the demuxer |stream|
+  // has been changed, the new status is |enabled| and the change occured while
+  // playback position was |time|.
+  void OnStreamStatusChanged(DemuxerStream* stream,
+                             bool enabled,
+                             base::TimeDelta time);
+
+  // Reinitialize audio/video renderer during a demuxer stream switching. The
+  // renderer must be flushed first, and when the re-init is completed the
+  // corresponding callback will be invoked to restart playback.
+  // The |stream| parameter specifies the new demuxer stream, and the |time|
+  // parameter specifies the time on media timeline where the switch occured.
+  void ReinitializeAudioRenderer(DemuxerStream* stream, base::TimeDelta time);
+  void OnAudioRendererReinitialized(DemuxerStream* stream,
+                                    base::TimeDelta time,
+                                    PipelineStatus status);
+  void ReinitializeVideoRenderer(DemuxerStream* stream, base::TimeDelta time);
+  void OnVideoRendererReinitialized(DemuxerStream* stream,
+                                    base::TimeDelta time,
+                                    PipelineStatus status);
+
+  // Restart audio/video renderer playback after a demuxer stream switch or
+  // after a demuxer stream has been disabled and re-enabled. The |stream|
+  // parameter specifies which stream needs to be restarted. The |time|
+  // parameter specifies the position on the media timeline where the playback
+  // needs to be restarted. It is necessary for demuxers with independent
+  // streams (e.g. MSE / ChunkDemuxer) to synchronize data reading between those
+  // streams.
+  void RestartAudioRenderer(DemuxerStream* stream, base::TimeDelta time);
+  void RestartVideoRenderer(DemuxerStream* stream, base::TimeDelta time);
 
   // Callback executed by filters to update statistics.
   void OnStatisticsUpdate(const PipelineStatistics& stats);
@@ -123,6 +147,7 @@ class MEDIA_EXPORT RendererImpl : public Renderer {
   //     and PausePlayback() should be called
   void OnBufferingStateChange(DemuxerStream::Type type,
                               BufferingState new_buffering_state);
+
   // Handles the buffering notifications that we might get while an audio or a
   // video stream is being restarted. In those cases we don't want to report
   // underflows immediately and instead give decoders a chance to catch up with
@@ -132,6 +157,7 @@ class MEDIA_EXPORT RendererImpl : public Renderer {
   bool HandleRestartedStreamBufferingChanges(
       DemuxerStream::Type type,
       BufferingState new_buffering_state);
+
   bool WaitingForEnoughData() const;
   void PausePlayback();
   void StartPlayback();
@@ -166,6 +192,9 @@ class MEDIA_EXPORT RendererImpl : public Renderer {
   std::unique_ptr<AudioRenderer> audio_renderer_;
   std::unique_ptr<VideoRenderer> video_renderer_;
 
+  DemuxerStream* current_audio_stream_;
+  DemuxerStream* current_video_stream_;
+
   // Renderer-provided time source used to control playback.
   TimeSource* time_source_;
   std::unique_ptr<WallClockTimeSource> wall_clock_time_source_;