WebmMuxer-MediaRecorderHandler: thread hopping and data ownership

content/renderer/media/media_recorder_handler.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_MEDIA_RECORDER_HANDLER_H_
 #define CONTENT_RENDERER_MEDIA_MEDIA_RECORDER_HANDLER_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
-#include "base/strings/string_piece.h"
 #include "base/threading/thread_checker.h"
 #include "content/common/content_export.h"
 #include "third_party/WebKit/public/platform/WebMediaRecorderHandler.h"
 #include "third_party/WebKit/public/platform/WebMediaStream.h"
 
 namespace blink {
 class WebMediaRecorderHandlerClient;
 class WebString;
 }  // namespace blink
 
 namespace media {
 class VideoFrame;
 class WebmMuxer;
 }  // namespace media
 
 namespace content {
 
 class VideoTrackRecorder;
 
-// MediaRecorderHandler orchestrates the creation, lifetime mgmt and mapping
-// between:
+// MediaRecorderHandler orchestrates the creation, lifetime management and
+// mapping between:
 // - MediaStreamTrack(s) providing data,
 // - {Audio,Video}TrackRecorders encoding that data,
 // - a WebmMuxer class multiplexing encoded data into a WebM container, and
 // - a single recorder client receiving this contained data.
 // All methods are called on the same thread as construction and destruction,
-// i.e. the Main Render thread.
-// TODO(mcasas): Implement audio recording.
+// i.e. the Main Render thread. (Note that a BindToCurrentLoop is used to
+// guarantee this, since VideoTrackRecorder sends back frames on IO thread.)
+// TODO(mcasas): http://crbug.com/528519 Implement audio recording.
 class CONTENT_EXPORT MediaRecorderHandler final
     : public NON_EXPORTED_BASE(blink::WebMediaRecorderHandler) {
  public:
   MediaRecorderHandler();
   ~MediaRecorderHandler() override;
 
-  // See above, these methods should override blink::WebMediaRecorderHandler.
+  // blink::WebMediaRecorderHandler.
   bool canSupportMimeType(const blink::WebString& mimeType) override;
   bool initialize(blink::WebMediaRecorderHandlerClient* client,
                   const blink::WebMediaStream& media_stream,
                   const blink::WebString& mimeType) override;
   bool start() override;
   bool start(int timeslice) override;
   void stop() override;
   void pause() override;
   void resume() override;
 
  private:
   friend class MediaRecorderHandlerTest;
 
-  void WriteData(const base::StringPiece& data);
+  void OnEncodedVideo(const scoped_refptr<media::VideoFrame>& video_frame,
+                      scoped_ptr<std::string> encoded_data,
+                      base::TimeTicks timestamp,
+                      bool is_key_frame);
+  void WriteData(scoped_ptr<std::string> data);

[miu, 2015/09/22 04:11:08]

FWICT, there was no need to change the WriteData() method.  See comment in
webm_muxer.cc.

[mcasas, 2015/09/22 16:58:40]

Acknowledged.

 
   void OnVideoFrameForTesting(const scoped_refptr<media::VideoFrame>& frame,
                               const base::TimeTicks& timestamp);
 
   // Bound to the main render thread.
   base::ThreadChecker main_render_thread_checker_;
 
   bool recording_;
   blink::WebMediaStream media_stream_;  // The MediaStream being recorded.
 
   // |client_| is a weak pointer, and is valid for the lifetime of this object.
   blink::WebMediaRecorderHandlerClient* client_;
 
   ScopedVector<VideoTrackRecorder> video_recorders_;
 
   // Worker class doing the actual Webm Muxing work.
   scoped_ptr<media::WebmMuxer> webm_muxer_;
 
   base::WeakPtrFactory<MediaRecorderHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaRecorderHandler);
 };
 
 }  // namespace content
 #endif  // CONTENT_RENDERER_MEDIA_MEDIA_RECORDER_HANDLER_H_