Replace trampolining in FFmpegDemuxer with explicit thread calling convention checks.

media/filters/ffmpeg_demuxer_unittest.cc

Index: media/filters/ffmpeg_demuxer_unittest.cc
diff --git a/media/filters/ffmpeg_demuxer_unittest.cc b/media/filters/ffmpeg_demuxer_unittest.cc
index e0dc371d26ca0cb18e3445d949001482a55fc4a5..bdb7547fe33e1c92cf433d8dd70367ff98a6a779 100644
--- a/media/filters/ffmpeg_demuxer_unittest.cc
+++ b/media/filters/ffmpeg_demuxer_unittest.cc
@@ -524,6 +524,7 @@ TEST_F(FFmpegDemuxerTest, DisableAudioStream) {
   // stream without requiring the message loop to read data.
   bool got_eos_buffer = false;
   audio->Read(base::Bind(&EosOnReadDone, &got_eos_buffer));
+  message_loop_.RunUntilIdle();
   EXPECT_TRUE(got_eos_buffer);
 }