MediaStream: Adding VideoTrackRecorder class and unittests

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 eb93e005a5ad7170929b80f2ab034aaa60ee80ba..fc8f05b20204cae560948017a1b92aae2d043f0e 100644
--- a/media/capture/webm_muxer.h
+++ b/media/capture/webm_muxer.h
@@ -9,6 +9,7 @@
 
 #include "base/callback.h"
 #include "base/gtest_prod_util.h"
+#include "base/memory/weak_ptr.h"
 #include "base/numerics/safe_math.h"
 #include "base/strings/string_piece.h"
 #include "base/threading/thread_checker.h"
@@ -23,8 +24,8 @@ namespace media {
 // Matroska container [2], composed of an EBML header, and a single Segment
 // including at least a Track Section and a number of SimpleBlocks each
 // containing a single encoded video frame. WebM container has no Trailer.
-// Clients will push encoded VPx video frames one by one via OnEncodedVideo()
-// with indication of the Track they belong to, and libwebm will eventually ping
+// Clients will push encoded VPx video frames one by one via the
+// OnEncodedVideoCB() returned by AddVideoTrack(). libwebm will eventually ping
 // the WriteDataCB passed on contructor with the wrapped encoded data. All
 // operations must happen in a single thread, where WebmMuxer is created and
 // destroyed.
@@ -41,14 +42,22 @@ class MEDIA_EXPORT WebmMuxer : public NON_EXPORTED_BASE(mkvmuxer::IMkvWriter) {
   explicit WebmMuxer(const WriteDataCB& write_data_callback);
   ~WebmMuxer() override;
 
-  // Creates and adds a new video track. Called before receiving the first
+  // 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. Returns the track_index to be used for OnEncodedVideo().
-  uint64_t AddVideoTrack(const gfx::Size& frame_size, double frame_rate);
+  // frame size. Returns OnEncodedVideo() callback with a |track_number| bound
+  // in the callback.
+  using OnEncodedVideoCB = base::Callback<void(const base::StringPiece& data,
+                                               base::TimeDelta timestamp,
+                                               bool is_key_frame)>;
+  OnEncodedVideoCB AddVideoTrack(const gfx::Size& frame_size,
+                                 double frame_rate);
+
+ private:
+  friend class WebmMuxerTest;
 
   // Adds a frame with |encoded_data.data()| to WebM Segment. |track_number| is
-  // a caller-side identifier and must have been provided by AddVideoTrack().
+  // a caller-side identifier and must have been returned by AddVideoTrack().
   // TODO(mcasas): Revisit how |encoded_data| is passed once the whole recording
   // chain is setup (http://crbug.com/262211).
   void OnEncodedVideo(uint64_t track_number,
@@ -56,9 +65,6 @@ class MEDIA_EXPORT WebmMuxer : public NON_EXPORTED_BASE(mkvmuxer::IMkvWriter) {
                       base::TimeDelta timestamp,
                       bool keyframe);
 
- private:
-  friend class WebmMuxerTest;
-
   // IMkvWriter interface.
   mkvmuxer::int32 Write(const void* buf, mkvmuxer::uint32 len) override;
   mkvmuxer::int64 Position() const override;
@@ -79,6 +85,8 @@ class MEDIA_EXPORT WebmMuxer : public NON_EXPORTED_BASE(mkvmuxer::IMkvWriter) {
   // The MkvMuxer active element.
   mkvmuxer::Segment segment_;
 
+  base::WeakPtrFactory<WebmMuxer> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(WebmMuxer);
 };