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

media/formats/webm/webm_stream_parser_unittest.cc

Index: media/formats/webm/webm_stream_parser_unittest.cc
diff --git a/media/formats/webm/webm_stream_parser_unittest.cc b/media/formats/webm/webm_stream_parser_unittest.cc
index 4afe163cf3377912dc805dc7659de77c04a34e8d..33af8e6deb95eeb5e37ccd9ca151c6a2d3e78a81 100644
--- a/media/formats/webm/webm_stream_parser_unittest.cc
+++ b/media/formats/webm/webm_stream_parser_unittest.cc
@@ -107,14 +107,14 @@ TEST_F(WebMStreamParserTest, VerifyMediaTrackMetadata) {
 
   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(), "");
   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(), "");
   EXPECT_EQ(audio_track.language(), "und");