Implement disabling and enabling media tracks

media/filters/chunk_demuxer.h

Index: media/filters/chunk_demuxer.h
diff --git a/media/filters/chunk_demuxer.h b/media/filters/chunk_demuxer.h
index ccb5a358df062e6ecc69b83e9f8d89e27bad44cd..a8a8d11d3e16f3ff0f86a0c937dc1632d198de56 100644
--- a/media/filters/chunk_demuxer.h
+++ b/media/filters/chunk_demuxer.h
@@ -105,6 +105,8 @@ class MEDIA_EXPORT ChunkDemuxerStream : public DemuxerStream {
   VideoDecoderConfig video_decoder_config() override;
   bool SupportsConfigChanges() override;
   VideoRotation video_rotation() override;
+  bool enabled() const override;
+  void set_enabled(bool enabled, base::TimeDelta timestamp) override;
 
   // Returns the text track configuration.  It is an error to call this method
   // if type() != TEXT.
@@ -144,6 +146,7 @@ class MEDIA_EXPORT ChunkDemuxerStream : public DemuxerStream {
   ReadCB read_cb_;
   bool splice_frames_enabled_;
   bool partial_append_window_trimming_enabled_;
+  bool is_enabled_ = true;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(ChunkDemuxerStream);
 };