Implement ISO BMFF support in Media Source (try 2).

media/filters/ffmpeg_audio_decoder.cc

Index: media/filters/ffmpeg_audio_decoder.cc
diff --git a/media/filters/ffmpeg_audio_decoder.cc b/media/filters/ffmpeg_audio_decoder.cc
index f48c0fa76e72badd208fd8e4ad3751f1d209f799..58f3dcd064a2abbfe0c5056d0d7f99f7e780dfab 100644
--- a/media/filters/ffmpeg_audio_decoder.cc
+++ b/media/filters/ffmpeg_audio_decoder.cc
@@ -11,6 +11,7 @@
 #include "media/base/demuxer.h"
 #include "media/base/pipeline.h"
 #include "media/ffmpeg/ffmpeg_common.h"
+#include "media/filters/ffmpeg_glue.h"
 
 namespace media {
 
@@ -49,6 +50,9 @@ void FFmpegAudioDecoder::Initialize(
     const scoped_refptr<DemuxerStream>& stream,
     const PipelineStatusCB& status_cb,
     const StatisticsCB& statistics_cb) {
+  // Ensure FFmpeg has been initialized
+  FFmpegGlue::GetInstance();
+
   if (!message_loop_) {
     message_loop_ = message_loop_factory_cb_.Run();
     message_loop_factory_cb_.Reset();