Unify media track info reporting on a demuxer level

media/blink/websourcebuffer_impl.h

Index: media/blink/websourcebuffer_impl.h
diff --git a/media/blink/websourcebuffer_impl.h b/media/blink/websourcebuffer_impl.h
index 1dc54e6f2a1497124d1395424d09ac2051065a77..b9b44049d97cb8e8239823f92bb236b2f4f66567 100644
--- a/media/blink/websourcebuffer_impl.h
+++ b/media/blink/websourcebuffer_impl.h
@@ -11,6 +11,7 @@
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "third_party/WebKit/public/platform/WebSourceBuffer.h"
 
@@ -43,7 +44,7 @@ class WebSourceBufferImpl : public blink::WebSourceBuffer {
  private:
   // Demuxer callback handler to process an initialization segment received
   // during an append() call.
-  void InitSegmentReceived(const MediaTracks& tracks);
+  void InitSegmentReceived(scoped_ptr<MediaTracks> tracks);
 
   std::string id_;
   ChunkDemuxer* demuxer_;  // Owned by WebMediaPlayerImpl.