Implemented passing media track info from ffmpeg into blink

media/base/demuxer.h

Index: media/base/demuxer.h
diff --git a/media/base/demuxer.h b/media/base/demuxer.h
index 5a2218a32663e1a66ba4519d690010ce165b1da1..b849f147aff1d8f374418c9d8fffbd51bc51d90f 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:
@@ -98,6 +99,11 @@ class MEDIA_EXPORT Demuxer : public DemuxerStreamProvider {
   // Returns the memory usage in bytes for the demuxer.
   virtual int64_t GetMemoryUsage() const = 0;
 
+  // Notifies demuxer clients that media track configuration has been updated
+  // (e.g. the inital stream metadata has been parsed successfully, or a new
+  // init segment has been parsed successfully in MSE case).
+  typedef base::Callback<void(scoped_ptr<MediaTracks>)> MediaTracksUpdatedCB;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(Demuxer);
 };