Refactor video capturing code in the render process

content/renderer/pepper/pepper_video_capture_host.h

 // Copyright (c) 2012 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_PEPPER_PEPPER_VIDEO_CAPTURE_HOST_H_
 #define CONTENT_RENDERER_PEPPER_PEPPER_VIDEO_CAPTURE_HOST_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/common/media/video_capture.h"
 #include "content/public/renderer/renderer_ppapi_host.h"
 #include "content/renderer/pepper/pepper_device_enumeration_host_helper.h"
 #include "content/renderer/pepper/ppb_buffer_impl.h"
-#include "media/video/capture/video_capture.h"
 #include "media/video/capture/video_capture_types.h"
 #include "ppapi/c/dev/ppp_video_capture_dev.h"
 #include "ppapi/host/host_message_context.h"
 #include "ppapi/host/resource_host.h"
 
+namespace media {
+class VideoFrame;
+}  // namespace media
+
 namespace content {
 class PepperPlatformVideoCapture;
 class RendererPpapiHostImpl;
 
-class PepperVideoCaptureHost : public ppapi::host::ResourceHost,
-                               public media::VideoCapture::EventHandler {
+class PepperVideoCaptureHost : public ppapi::host::ResourceHost {
  public:
   PepperVideoCaptureHost(RendererPpapiHostImpl* host,
                          PP_Instance instance,
                          PP_Resource resource);
 
   virtual ~PepperVideoCaptureHost();
 
   bool Init();
 
   virtual int32_t OnResourceMessageReceived(
       const IPC::Message& msg,
       ppapi::host::HostMessageContext* context) OVERRIDE;
 
-  void OnInitialized(media::VideoCapture* capture, bool succeeded);
+  void OnInitialized(bool succeeded);
 
-  // media::VideoCapture::EventHandler
-  virtual void OnStarted(media::VideoCapture* capture) OVERRIDE;
-  virtual void OnStopped(media::VideoCapture* capture) OVERRIDE;
-  virtual void OnPaused(media::VideoCapture* capture) OVERRIDE;
-  virtual void OnError(media::VideoCapture* capture, int error_code) OVERRIDE;
-  virtual void OnRemoved(media::VideoCapture* capture) OVERRIDE;
-  virtual void OnFrameReady(media::VideoCapture* capture,
-                            const scoped_refptr<media::VideoFrame>& frame)
-      OVERRIDE;
+  void OnStarted();

[Ami GONE FROM CHROMIUM, 2014/04/21 23:42:53]

It's strange to see methods like this not be OVERRIDEs or =0 or documented.  
I wonder whether you could get away with exposing only getters for the CB
(bound) versions of these methods?

[Alpha Left Google, 2014/04/23 18:48:33]

I added documents for these methods. PepperVidoeCaptureHost is accessed by
PapperPlatformVideoCapture directly without callbacks, in other ways than video
frame delivery and state changes. I would like to keep it this way but get rid
of the inheritance. 

+  void OnStopped();
+  void OnPaused();
+  void OnError();
+  void OnFrameReady(const scoped_refptr<media::VideoFrame>& frame,
+                    media::VideoCaptureFormat format);
 
  private:
   int32_t OnOpen(ppapi::host::HostMessageContext* context,
                  const std::string& device_id,
                  const PP_VideoCaptureDeviceInfo_Dev& requested_info,
                  uint32_t buffer_count);
   int32_t OnStartCapture(ppapi::host::HostMessageContext* context);
   int32_t OnReuseBuffer(ppapi::host::HostMessageContext* context,
                         uint32_t buffer);
   int32_t OnStopCapture(ppapi::host::HostMessageContext* context);
   int32_t OnClose(ppapi::host::HostMessageContext* context);
 
   int32_t StopCapture();
   int32_t Close();
   void PostErrorReply();
   void AllocBuffers(const gfx::Size& resolution, int frame_rate);
   void ReleaseBuffers();
   void SendStatus();
 
   void SetRequestedInfo(const PP_VideoCaptureDeviceInfo_Dev& device_info,
                         uint32_t buffer_count);
 
   void DetachPlatformVideoCapture();
 
   bool SetStatus(PP_VideoCaptureStatus_Dev status, bool forced);
 
-  scoped_refptr<PepperPlatformVideoCapture> platform_video_capture_;
+  scoped_ptr<PepperPlatformVideoCapture> platform_video_capture_;
 
   // Buffers of video frame.
   struct BufferInfo {
     BufferInfo();
     ~BufferInfo();
 
     bool in_use;
     void* data;
     scoped_refptr<PPB_Buffer_Impl> buffer;
   };
@@ skipping 11 matching lines @@
   ppapi::host::ReplyMessageContext open_reply_context_;
 
   PepperDeviceEnumerationHostHelper enumeration_helper_;
 
   DISALLOW_COPY_AND_ASSIGN(PepperVideoCaptureHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_PEPPER_PEPPER_VIDEO_CAPTURE_HOST_H_