Implement disabling and enabling media tracks

media/mojo/interfaces/demuxer_stream.mojom

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module media.mojom;
 
 import "media/mojo/interfaces/media_types.mojom";
 
 // DemuxerStream is modeled after media::DemuxerStream using mojo in order to
 // enable proxying between a media::Pipeline and media::Renderer living in two
@@ skipping 39 matching lines @@
   // into the DataPipe given to Initialize() once DataPipe supports framed data
   // in a nicer fashion.
   Read() => (Status status,
              DecoderBuffer? buffer,
              AudioDecoderConfig? audio_config,
              VideoDecoderConfig? video_config);
 
   // Enables converting bitstream to a format that is expected by the decoder.
   // For example, H.264/AAC bitstream based packets into H.264 Annex B format.
   EnableBitstreamConverter();
+
+  enabled() => (bool enabled);
+  set_enabled(bool enabled, int64 time_usec);
 };