Emit Media Source codec names as media_log events.

media/filters/chunk_demuxer.h

Index: media/filters/chunk_demuxer.h
diff --git a/media/filters/chunk_demuxer.h b/media/filters/chunk_demuxer.h
index 18b6cb5f1169f2c512f26aeab9d68efd3f28558f..d778db65c8d5d8cb4db34c29c25486c271ad7203 100644
--- a/media/filters/chunk_demuxer.h
+++ b/media/filters/chunk_demuxer.h
@@ -157,6 +157,7 @@ class MEDIA_EXPORT ChunkDemuxer : public Demuxer {
   ChunkDemuxer(const base::Closure& open_cb,
                const NeedKeyCB& need_key_cb,
                const LogCB& log_cb,
+               const scoped_refptr<MediaLog>& media_log,
                bool splice_frames_enabled);
   ~ChunkDemuxer() override;
 
@@ -361,6 +362,7 @@ class MEDIA_EXPORT ChunkDemuxer : public Demuxer {
   // Callback used to report error strings that can help the web developer
   // figure out what is wrong with the content.
   LogCB log_cb_;
+  scoped_refptr<MediaLog> media_log_;
 
   PipelineStatusCB init_cb_;
   // Callback to execute upon seek completion.