Fix supported codecs for mp2t container

We support only a limited subset of a/v codecs in mpeg2ts container:
H264, AAC, MP3 (see Mp2tStreamParser::RegisterPes). So adjust the
mime_util codec set accordingly.

Bug: internal b/110705267
Test: check isTypeSupported('video/mp2t; codecs=ac-3') on Chromecast
Change-Id: Ib9bcd0e2fb06603a5a15927f6bcaf4e721a063d4
Reviewed-on: https://chromium-review.googlesource.com/1183698Reviewed-by: Thomas Guilbert <tguilbert@chromium.org>
Commit-Queue: Sergey Volk <servolk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584867}

media/base/mime_util_internal.cc

@@ -349,9 +349,8 @@ void MimeUtil::AddSupportedMediaFormats() {
   AddContainerWithCodecs("video/x-m4v", avc_and_aac, true);
 
 #if BUILDFLAG(ENABLE_MSE_MPEG2TS_STREAM_PARSER)
-  // TODO(ddorwin): Exactly which codecs should be supported?
-  DCHECK(!mp4_video_codecs.empty());
-  AddContainerWithCodecs("video/mp2t", mp4_codecs, true);
+  CodecSet mp2t_codecs{H264, MPEG2_AAC, MPEG4_AAC, MP3};
+  AddContainerWithCodecs("video/mp2t", mp2t_codecs, true);
 #endif  // BUILDFLAG(ENABLE_MSE_MPEG2TS_STREAM_PARSER)
 #if defined(OS_ANDROID)
   // HTTP Live Streaming (HLS).