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

media/formats/mp2t/mp2t_stream_parser.cc

Index: media/formats/mp2t/mp2t_stream_parser.cc
diff --git a/media/formats/mp2t/mp2t_stream_parser.cc b/media/formats/mp2t/mp2t_stream_parser.cc
index 041bc0d1d0ef7199eadc7f81e046785b2ca2166c..9f43d2d14a746266cd2cece9bc393a484a473e2d 100644
--- a/media/formats/mp2t/mp2t_stream_parser.cc
+++ b/media/formats/mp2t/mp2t_stream_parser.cc
@@ -512,10 +512,10 @@ std::unique_ptr<MediaTracks> GenerateMediaTrackInfo(
   // TODO(servolk): Implement proper sourcing of media track info as described
   // in crbug.com/590085
   if (audio_config.IsValidConfig()) {
-    media_tracks->AddAudioTrack(audio_config, "audio", "main", "", "");
+    media_tracks->AddAudioTrack(audio_config, 1, "main", "", "");
   }
   if (video_config.IsValidConfig()) {
-    media_tracks->AddVideoTrack(video_config, "video", "main", "", "");
+    media_tracks->AddVideoTrack(video_config, 2, "main", "", "");
   }
   return media_tracks;
 }