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

media/formats/mp4/mp4_stream_parser_unittest.cc

Index: media/formats/mp4/mp4_stream_parser_unittest.cc
diff --git a/media/formats/mp4/mp4_stream_parser_unittest.cc b/media/formats/mp4/mp4_stream_parser_unittest.cc
index e84a85b70c14b88b3ce2a6c8a31ca4d7ccee2621..a4f70714b8a9f47542cf88f7df39e77305c11deb 100644
--- a/media/formats/mp4/mp4_stream_parser_unittest.cc
+++ b/media/formats/mp4/mp4_stream_parser_unittest.cc
@@ -499,14 +499,14 @@ TEST_F(MP4StreamParserTest, MediaTrackInfoSourcing) {
   EXPECT_EQ(media_tracks_->tracks().size(), 2u);
   const MediaTrack& video_track = *(media_tracks_->tracks()[0]);
   EXPECT_EQ(video_track.type(), MediaTrack::Video);
-  EXPECT_EQ(video_track.id(), "1");
+  EXPECT_EQ(video_track.id(), 1);
   EXPECT_EQ(video_track.kind(), "main");
   EXPECT_EQ(video_track.label(), "VideoHandler");
   EXPECT_EQ(video_track.language(), "und");
 
   const MediaTrack& audio_track = *(media_tracks_->tracks()[1]);
   EXPECT_EQ(audio_track.type(), MediaTrack::Audio);
-  EXPECT_EQ(audio_track.id(), "2");
+  EXPECT_EQ(audio_track.id(), 2);
   EXPECT_EQ(audio_track.kind(), "main");
   EXPECT_EQ(audio_track.label(), "SoundHandler");
   EXPECT_EQ(audio_track.language(), "und");