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

media/formats/mpeg/mpeg_audio_stream_parser_base.cc

Index: media/formats/mpeg/mpeg_audio_stream_parser_base.cc
diff --git a/media/formats/mpeg/mpeg_audio_stream_parser_base.cc b/media/formats/mpeg/mpeg_audio_stream_parser_base.cc
index 6e0a3837bcd1b43e9b02c3637c71c21c7dfdc73d..016f9789a03cda4799b32cced6b22633ff70f416 100644
--- a/media/formats/mpeg/mpeg_audio_stream_parser_base.cc
+++ b/media/formats/mpeg/mpeg_audio_stream_parser_base.cc
@@ -221,7 +221,7 @@ int MPEGAudioStreamParserBase::ParseFrame(const uint8_t* data,
 
     std::unique_ptr<MediaTracks> media_tracks(new MediaTracks());
     if (config_.IsValidConfig()) {
-      media_tracks->AddAudioTrack(config_, "audio", "", "", "");
+      media_tracks->AddAudioTrack(config_, 1, "main", "", "");
     }
     if (!config_cb_.Run(std::move(media_tracks), TextTrackConfigMap()))
       return -1;