Use StreamParser::TrackId instead of string for MediaTrack::byteStreamTrackId

media/base/media_track.h

Index: media/base/media_track.h
diff --git a/media/base/media_track.h b/media/base/media_track.h
index a5cb6d3d81817b1d77f57f221a4cb7a05c8739ca..de9cbf6215afd18f635c77fcbf6f909f39f38693 100644
--- a/media/base/media_track.h
+++ b/media/base/media_track.h
@@ -8,6 +8,7 @@
 #include <string>
 
 #include "media/base/media_export.h"
+#include "media/base/stream_parser.h"
 
 namespace media {
 
@@ -15,7 +16,7 @@ class MEDIA_EXPORT MediaTrack {
  public:
   enum Type { Text, Audio, Video };
   MediaTrack(Type type,
-             const std::string& id,
+             StreamParser::TrackId id,
              const std::string& kind,
              const std::string& label,
              const std::string& lang);
@@ -23,14 +24,14 @@ class MEDIA_EXPORT MediaTrack {
 
   Type type() const { return type_; }
 
-  const std::string& id() const { return id_; }
+  StreamParser::TrackId id() const { return id_; }
   const std::string& kind() const { return kind_; }
   const std::string& label() const { return label_; }
   const std::string& language() const { return language_; }
 
  private:
   Type type_;
-  std::string id_;
+  StreamParser::TrackId id_;
   std::string kind_;
   std::string label_;
   std::string language_;