VideoTrackRecorder: extract base class Encoder out of VpxEncoder

content/renderer/media/video_track_recorder.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_MEDIA_VIDEO_TRACK_RECORDER_H_
 #define CONTENT_RENDERER_MEDIA_VIDEO_TRACK_RECORDER_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/thread_checker.h"
 #include "content/public/renderer/media_stream_video_sink.h"
 #include "third_party/WebKit/public/platform/WebMediaStreamTrack.h"
 
 namespace media {
 class VideoFrame;
 }  // namespace media
 
 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
-// Render thread but that pass frames on Render IO thread.
+// received from a Stream Video Track. This class is constructed and used on a
+// single thread, namely the main Render thread. This mirrors the other
+// MediaStreamVideo* classes that are constructed/configured on Main Render
+// thread but that pass frames on Render IO thread. It has an internal Encoder
+// with its own threading subtleties, see the implementation file.
 class CONTENT_EXPORT VideoTrackRecorder
     : NON_EXPORTED_BASE(public MediaStreamVideoSink) {
  public:
   enum class CodecId {
     VP8,
     VP9,
   };
+  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)>;
 
   VideoTrackRecorder(CodecId codec,
                      const blink::WebMediaStreamTrack& track,
                      const OnEncodedVideoCB& on_encoded_video_cb,
                      int32_t bits_per_second);
   ~VideoTrackRecorder() override;
 
   void Pause();
   void Resume();
 
   void OnVideoFrameForTesting(const scoped_refptr<media::VideoFrame>& frame,
                               base::TimeTicks capture_time);
  private:
   friend class VideoTrackRecorderTest;
 
   // Used to check that we are destroyed on the same thread we were created.
   base::ThreadChecker main_render_thread_checker_;
 
   // We need to hold on to the Blink track to remove ourselves on dtor.
   blink::WebMediaStreamTrack track_;
 
   // Inner class to encode using whichever codec is configured.
-  class VpxEncoder;
-  const scoped_refptr<VpxEncoder> encoder_;
+  const scoped_refptr<Encoder> encoder_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoTrackRecorder);
 };
 
 }  // namespace content
 #endif  // CONTENT_RENDERER_MEDIA_VIDEO_TRACK_RECORDER_H_