Re-add AC3/EAC3 audio demuxing support

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 9d3d169928f07abef11527e76f7ba8f19441d483..3995c7d4c7592f6094bb449d63938fdaa469a8c9 100644
--- a/media/formats/mp4/mp4_stream_parser_unittest.cc
+++ b/media/formats/mp4/mp4_stream_parser_unittest.cc
@@ -338,5 +338,21 @@ TEST_F(MP4StreamParserTest, NaturalSizeWithPASP) {
   EXPECT_EQ(gfx::Size(639, 360), video_decoder_config_.natural_size());
 }
 
+#if defined(ENABLE_AC3_EAC3_AUDIO_DEMUXING)

[ddorwin, 2016/01/04 23:22:18]

As before, can we expect a graceful failure when not enabled?

[servolk, 2016/01/07 02:30:04]

No other tests do that, so currently the helper classes are structured in a way
that don't make it easy. Besides - how do we define 'graceful failure'? Failure
anywhere in the code, but not a crash? Or failure at a specific place in the
media stack with a specific error code?
I'd prefer to make that a separate change.

[ddorwin, 2016/01/07 19:12:43]

Failure without crashing or hanging (timeout).

[servolk, 2016/01/07 21:17:36]

Ok, I'll see if we can do this easily here.

[servolk, 2016/01/08 00:53:33]

I guess we could do something like this
https://codereview.chromium.org/1567783005/
And something similar for HEVC. But I'd still prefer this to be a separate CL

+TEST_F(MP4StreamParserTest, DemuxingAC3) {
+  std::set<int> audio_object_types;
+  audio_object_types.insert(kAC3);
+  parser_.reset(new MP4StreamParser(audio_object_types, false));
+  ParseMP4File("bear-ac3-frag.mp4", 512);

[ddorwin, 2016/01/04 23:22:18]

Comments on test files:

* Do these files have video? If so, include the video codec, if not, consider
adding "-only" like bear-mpeg2-aac-only_frag.mp4.
* Please update the README with how they were created.

[servolk, 2016/01/07 02:30:04]

No, these are audio-only files, renamed. Also updated README with ffmpeg command
lines.

+}
+
+TEST_F(MP4StreamParserTest, DemuxingEAC3) {
+  std::set<int> audio_object_types;
+  audio_object_types.insert(kEAC3);
+  parser_.reset(new MP4StreamParser(audio_object_types, false));
+  ParseMP4File("bear-eac3-frag.mp4", 512);
+}
+#endif
+
 }  // namespace mp4
 }  // namespace media