[experimental] MR: add support for H264 recording

media/muxers/webm_muxer.h

Index: media/muxers/webm_muxer.h
diff --git a/media/muxers/webm_muxer.h b/media/muxers/webm_muxer.h
index 1dd6c6593a73b95d42bebdf88d6911e20f2333af..32a71866c76f1f0b3f411dd0976159eb634b6080 100644
--- a/media/muxers/webm_muxer.h
+++ b/media/muxers/webm_muxer.h
@@ -96,8 +96,8 @@ class MEDIA_EXPORT WebmMuxer : public NON_EXPORTED_BASE(mkvmuxer::IMkvWriter) {
   // Used to DCHECK that we are called on the correct thread.
   base::ThreadChecker thread_checker_;
 
-  // Video Codec configured: VP9 if true, otherwise VP8 is used by default.
-  const bool use_vp9_;
+  // Video Codec configured on construction.
+  const VideoCodec codec_;
 
   // Caller-side identifiers to interact with |segment_|, initialised upon
   // first frame arrival to Add{Video, Audio}Track().