MediaStream: Adding VideoTrackRecorder class and unittests

media/capture/webm_muxer.cc

Index: media/capture/webm_muxer.cc
diff --git a/media/capture/webm_muxer.cc b/media/capture/webm_muxer.cc
index 8f6704101308e3f6e9e1fb6476e4090cfbab5100..a04901b9d1b7aee8705d11aeb4661b7c76d0b215 100644
--- a/media/capture/webm_muxer.cc
+++ b/media/capture/webm_muxer.cc
@@ -6,11 +6,14 @@
 
 #include <limits>
 
+#include "base/bind.h"
+
 namespace media {
 
 WebmMuxer::WebmMuxer(const WriteDataCB& write_data_callback)
     : write_data_callback_(write_data_callback),
-      position_(0) {
+      position_(0),
+      weak_factory_(this) {
   DCHECK(thread_checker_.CalledOnValidThread());
   segment_.Init(this);
   segment_.set_mode(mkvmuxer::Segment::kLive);
@@ -26,8 +29,8 @@ WebmMuxer::~WebmMuxer() {
   segment_.Finalize();
 }
 
-uint64_t WebmMuxer::AddVideoTrack(const gfx::Size& frame_size,
-                                  double frame_rate) {
+WebmMuxer::OnEncodedVideoCB
+WebmMuxer::AddVideoTrack(const gfx::Size& frame_size, double frame_rate) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   const uint64_t track_index =
@@ -50,7 +53,8 @@ uint64_t WebmMuxer::AddVideoTrack(const gfx::Size& frame_size,
   // http://www.webmproject.org/docs/container/#muxer-guidelines
   DCHECK_EQ(segment_.GetSegmentInfo()->timecode_scale(), 1000000ull);
 
-  return track_index;
+  return base::Bind(&WebmMuxer::OnEncodedVideo, weak_factory_.GetWeakPtr(),
+                    track_index);
 }
 
 void WebmMuxer::OnEncodedVideo(uint64_t track_number,