MediaStream Recorder: Support VP9 encoder

media/capture/webm_muxer.h

Index: media/capture/webm_muxer.h
diff --git a/media/capture/webm_muxer.h b/media/capture/webm_muxer.h
index 2d25c46a66a40342f8f2e4484dafee2662bf677e..f4ac5ac9be4dd1552b29cc21df8b3470768bc1f1 100644
--- a/media/capture/webm_muxer.h
+++ b/media/capture/webm_muxer.h
@@ -40,7 +40,7 @@ class MEDIA_EXPORT WebmMuxer : public NON_EXPORTED_BASE(mkvmuxer::IMkvWriter) {
   // either any file header or a SingleBlock.
   using WriteDataCB = base::Callback<void(base::StringPiece)>;
 
-  explicit WebmMuxer(const WriteDataCB& write_data_callback);
+   WebmMuxer(bool use_vp9, const WriteDataCB& write_data_callback);

[miu, 2015/10/07 18:16:35]

Please add a comment that VP8 will be used if |use_vp9| is false.

Alternatively, consider using a "const char* codec_id" argument instead, where
|codec_id| must match one of the constants in mkvmuxer.hpp
(https://code.google.com/p/chromium/codesearch#chromium/src/third_party/libweb...).

[mcasas, 2015/10/07 21:01:15]

Done.
Wouldn't that surface implementation details? IOW the owner/ctor of this
class will have to know a detail of how libwebm identifies codecs.

[miu, 2015/10/07 21:56:56]

Yeah, that's a good point.  I suppose I'm fine with leaving it the way it is.

   ~WebmMuxer() override;
 
   // Adds a |video_frame| with |encoded_data.data()| to WebM Segment.
@@ -69,6 +69,8 @@ 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_;
 
+  const bool use_vp9_;

[miu, 2015/10/07 18:16:35]

ditto: comment that meaning of "false" means VP8

[mcasas, 2015/10/07 21:01:14]

Done.

+
   // A caller-side identifier to interact with |segment_|, initialised upon
   // first frame arrival by AddVideoTrack().
   uint64_t track_index_;