Unify media track info reporting on a demuxer level

media/base/demuxer.h

Index: media/base/demuxer.h
diff --git a/media/base/demuxer.h b/media/base/demuxer.h
index 5a2218a32663e1a66ba4519d690010ce165b1da1..799d6d0ff08c144bb3d571403ca69aa1c9c65beb 100644
--- a/media/base/demuxer.h
+++ b/media/base/demuxer.h
@@ -22,6 +22,7 @@
 namespace media {
 
 class TextTrackConfig;
+class MediaTracks;
 
 class MEDIA_EXPORT DemuxerHost {
  public:
@@ -61,6 +62,11 @@ class MEDIA_EXPORT Demuxer : public DemuxerStreamProvider {
                               const std::vector<uint8_t>& init_data)>
       EncryptedMediaInitDataCB;
 
+  // Notifies demuxer clients that media track configuration has been updated
+  // (e.g. the inital stream metadata has been parsed successfully, or a new

[wolenetz, 2016/03/05 01:47:43]

nit:initial

+  // init segment has been parsed successfully in MSE case).
+  typedef base::Callback<void(scoped_ptr<MediaTracks>)> MediaTracksUpdatedCB;
+
   Demuxer();
   ~Demuxer() override;