Implemented Multiple video track recoding.

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 3fec647fa9cc3e8aecb5a53220392e4541eb5376..bdd1892c2192a87e450e0c44c1ac4a2e8363cc25 100644
--- a/media/capture/webm_muxer.h
+++ b/media/capture/webm_muxer.h
@@ -46,19 +46,30 @@ class MEDIA_EXPORT WebmMuxer : public NON_EXPORTED_BASE(mkvmuxer::IMkvWriter) {
   // Adds a |video_frame| with |encoded_data.data()| to WebM Segment.
   // TODO(mcasas): Revisit how |encoded_data| is passed once the whole recording
   // chain is setup (http://crbug.com/262211).
-  void OnEncodedVideo(const scoped_refptr<VideoFrame>& video_frame,
+  void OnEncodedVideo(int track_index,
+                      const scoped_refptr<VideoFrame>& video_frame,
                       const base::StringPiece& encoded_data,
                       base::TimeTicks timestamp,
                       bool is_key_frame);
 
+  int GetNextTrackIndex();
+
  private:
   friend class WebmMuxerTest;
+  struct MuxerArg {

[ajose, 2015/09/18 18:28:58]

Change to VideoMuxerArg or similar? These tests will eventually need to test
audio too, so nice to have clear names in this regard.

[msu.koo, 2015/09/21 04:28:37]

Done.

+    MuxerArg(const base::TimeTicks& first_frame_timestamp, uint64 track_number)
+        : first_frame_timestamp(first_frame_timestamp),
+          track_number(track_number) {}
+
+    base::TimeTicks first_frame_timestamp;
+    uint64 track_number;
+  };
 
   // Creates and adds a new video track. Called upon receiving the first
   // frame of a given Track, adds |frame_size| and |frame_rate| to the Segment
   // info, although individual frames passed to OnEncodedVideo() can have any
   // frame size.
-  void AddVideoTrack(const gfx::Size& frame_size, double frame_rate);
+  uint64 AddVideoTrack(const gfx::Size& frame_size, double frame_rate);
 
   // IMkvWriter interface.
   mkvmuxer::int32 Write(const void* buf, mkvmuxer::uint32 len) override;
@@ -71,12 +82,8 @@ class MEDIA_EXPORT WebmMuxer : public NON_EXPORTED_BASE(mkvmuxer::IMkvWriter) {
   // Used to DCHECK that we are called on the correct thread (usually IO)
   base::ThreadChecker thread_checker_;
 
-  // A caller-side identifier to interact with |segment_|, initialised upon
-  // first frame arrival by AddVideoTrack().
-  uint64_t track_index_;
-
-  // Origin of times for frame timestamps.
-  base::TimeTicks first_frame_timestamp_;
+  // Arguments for each tracks to mkvmuxer.
+  std::vector<MuxerArg> muxer_args;

[ajose, 2015/09/18 18:28:58]

muxer_args_ (or muxer_args_for_video_ or something)

[msu.koo, 2015/09/21 04:28:37]

Done.

 
   // Callback to dump written data as being called by libwebm.
   const WriteDataCB write_data_callback_;