[experimental] MR: add support for H264 recording

content/renderer/media/video_track_recorder.h

Index: content/renderer/media/video_track_recorder.h
diff --git a/content/renderer/media/video_track_recorder.h b/content/renderer/media/video_track_recorder.h
index 971257bf7263470b1014d5d23eb96de6f0522555..b9094f528ed7de509d06267d4a4d8de13af0c931 100644
--- a/content/renderer/media/video_track_recorder.h
+++ b/content/renderer/media/video_track_recorder.h
@@ -21,21 +21,28 @@ namespace content {
 
 // VideoTrackRecorder is a MediaStreamVideoSink that encodes the video frames
 // received from a Stream Video Track. The class is constructed and used on a
-// single thread, namely the main Render thread. It has an internal VpxEncoder
-// with its own threading subtleties, see the implementation file. This mirrors
-// the other MediaStreamVideo* classes that are constructed/configured on Main
+// single thread, namely the main Render thread. It has an internal Encoder with
+// its own threading subtleties, see the implementation file. This mirrors the
+// other MediaStreamVideo* classes that are constructed/configured on Main
 // Render thread but that pass frames on Render IO thread.
 class CONTENT_EXPORT VideoTrackRecorder
     : NON_EXPORTED_BASE(public MediaStreamVideoSink) {
  public:
+  enum class CodecId {
+    VP8,
+    VP9,
+    H264,
+    MAX = H264
+  };
+  class Encoder;
+
   using OnEncodedVideoCB =
       base::Callback<void(const scoped_refptr<media::VideoFrame>& video_frame,
                           std::unique_ptr<std::string> encoded_data,
                           base::TimeTicks capture_timestamp,
                           bool is_key_frame)>;
 
-  // |use_vp9| forces using VP9, otherwise VP8 will be used by default.
-  VideoTrackRecorder(bool use_vp9,
+  VideoTrackRecorder(CodecId codec,
                      const blink::WebMediaStreamTrack& track,
                      const OnEncodedVideoCB& on_encoded_video_cb,
                      int32_t bits_per_second);
@@ -55,9 +62,8 @@ class CONTENT_EXPORT VideoTrackRecorder
   // We need to hold on to the Blink track to remove ourselves on dtor.
   blink::WebMediaStreamTrack track_;
 
-  // Forward declaration and member of an inner class to encode using VPx.
-  class VpxEncoder;
-  const scoped_refptr<VpxEncoder> encoder_;
+  // Forward declaration and member of an inner class to encode.
+  scoped_refptr<Encoder> encoder_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoTrackRecorder);
 };