Allow muting/unmuting audio through media track API

media/filters/ffmpeg_demuxer.cc

Index: media/filters/ffmpeg_demuxer.cc
diff --git a/media/filters/ffmpeg_demuxer.cc b/media/filters/ffmpeg_demuxer.cc
index e9b602fa4226cfee539de7f533ae36a35f364476..7c31f079fa821810bd5dcbf7b8c60a0e737e72e1 100644
--- a/media/filters/ffmpeg_demuxer.cc
+++ b/media/filters/ffmpeg_demuxer.cc
@@ -1112,6 +1112,7 @@ void FFmpegDemuxer::OnFindStreamInfoDone(const PipelineStatusCB& status_cb,
   }
 
   scoped_ptr<MediaTracks> media_tracks(new MediaTracks());
+  MediaTracks::TrackToDemuxStreamMap track_to_demux_stream_map;
   AVStream* audio_stream = NULL;
   AudioDecoderConfig audio_config;
   AVStream* video_stream = NULL;
@@ -1205,22 +1206,25 @@ void FFmpegDemuxer::OnFindStreamInfoDone(const PipelineStatusCB& status_cb,
 
     // Note when we find our audio/video stream (we only want one of each) and
     // record src= playback UMA stats for the stream's decoder config.
+    const MediaTrack* media_track = nullptr;
     if (codec_type == AVMEDIA_TYPE_AUDIO) {
       CHECK(!audio_stream);
       audio_stream = stream;
       audio_config = streams_[i]->audio_decoder_config();
       RecordAudioCodecStats(audio_config);
 
-      media_tracks->AddAudioTrack(audio_config, track_id, "main", track_label,
-                                  track_language);
+      media_track = media_tracks->AddAudioTrack(audio_config, track_id, "main",
+                                                track_label, track_language);
+      track_to_demux_stream_map[media_track] = streams_[i];
     } else if (codec_type == AVMEDIA_TYPE_VIDEO) {
       CHECK(!video_stream);
       video_stream = stream;
       video_config = streams_[i]->video_decoder_config();
       RecordVideoCodecStats(video_config, stream->codec->color_range);
 
-      media_tracks->AddVideoTrack(video_config, track_id, "main", track_label,
-                                  track_language);
+      media_track = media_tracks->AddVideoTrack(video_config, track_id, "main",
+                                                track_label, track_language);
+      track_to_demux_stream_map[media_track] = streams_[i];
     }
 
     max_duration = std::max(max_duration, streams_[i]->duration());
@@ -1396,6 +1400,7 @@ void FFmpegDemuxer::OnFindStreamInfoDone(const PipelineStatusCB& status_cb,
   metadata_event->params.SetInteger("bitrate", bitrate_);
   media_log_->AddEvent(std::move(metadata_event));
 
+  media_tracks->set_track_to_demux_stream_map(track_to_demux_stream_map);
   media_tracks_updated_cb_.Run(std::move(media_tracks));
 
   status_cb.Run(PIPELINE_OK);
@@ -1579,4 +1584,27 @@ void FFmpegDemuxer::SetLiveness(DemuxerStream::Liveness liveness) {
   }
 }
 
+void FFmpegDemuxer::OnTrackIdsAssigned(const MediaTracks& tracks,
+                                       const std::vector<unsigned>& track_ids) {
+  DCHECK_EQ(tracks.tracks().size(), track_ids.size());
+  const auto& track_to_demux_stream = tracks.track_to_demux_stream_map();
+  DCHECK_EQ(track_to_demux_stream.size(), tracks.tracks().size());
+  for (size_t i = 0; i < track_ids.size(); ++i) {
+    const MediaTrack* track = tracks.tracks()[i].get();
+    DCHECK(track);
+    const auto& it = track_to_demux_stream.find(track);
+    DCHECK(it != track_to_demux_stream.end());
+    DVLOG(3) << "OnTrackIdsAssigned track_id=" << track_ids[i]
+             << " DemuxerStream=" << it->second;
+    track_id_to_demux_stream_[track_ids[i]] = it->second;
+  }
+}
+
+const DemuxerStream* FFmpegDemuxer::GetDemuxerStreamByTrackId(
+    unsigned track_id) const {
+  const auto& it = track_id_to_demux_stream_.find(track_id);
+  CHECK(it != track_id_to_demux_stream_.end());
+  return it->second;
+}
+
 }  // namespace media