Implement disabling and enabling media tracks

media/base/pipeline_impl.h

Index: media/base/pipeline_impl.h
diff --git a/media/base/pipeline_impl.h b/media/base/pipeline_impl.h
index 3a8a90a0ac58d6914c4a9e49e4f134e9b646da14..49788f10e81063638f083150f0e23034a0ae8792 100644
--- a/media/base/pipeline_impl.h
+++ b/media/base/pipeline_impl.h
@@ -94,6 +94,8 @@ class MEDIA_EXPORT PipelineImpl : public Pipeline,
              std::unique_ptr<Renderer> renderer,
              Client* client,
              const PipelineStatusCB& seek_cb) override;
+  void RestartStreamPlayback(DemuxerStream* stream,
+                             base::TimeDelta time) override;
   void Stop() override;
   void Seek(base::TimeDelta time, const PipelineStatusCB& seek_cb) override;
   bool IsRunning() const override;
@@ -164,6 +166,8 @@ class MEDIA_EXPORT PipelineImpl : public Pipeline,
   // task runner.
   void StartTask();
 
+  void RestartStreamPlaybackTask(DemuxerStream* stream, base::TimeDelta time);
+
   // Suspends the pipeline, discarding the current renderer.
   void SuspendTask(const PipelineStatusCB& suspend_cb);