Revert 244074 "Eliminate video capture thread in renderer"

trunk/src/content/renderer/media/video_capture_impl.h

Index: trunk/src/content/renderer/media/video_capture_impl.h
===================================================================
--- trunk/src/content/renderer/media/video_capture_impl.h	(revision 244357)
+++ trunk/src/content/renderer/media/video_capture_impl.h	(working copy)
@@ -9,21 +9,23 @@
 // VideoCaptureImpl is also a delegate of VideoCaptureMessageFilter which relays
 // operation of a capture device to the browser process and receives responses
 // from browser process.
+
+// The media::VideoCapture and VideoCaptureMessageFilter::Delegate are
+// asynchronous interfaces, which means callers can call those interfaces
+// from any threads without worrying about thread safety.
+// The |capture_message_loop_proxy_| is the working thread of VideoCaptureImpl.
+// All non-const members are accessed only on that working thread.
 //
-// All public methods of VideoCaptureImpl can be called on any thread.
-// Internally it runs on the IO thread. Clients of this class implement
-// interface media::VideoCapture::EventHandler which is called only on the IO
-// thread.
-//
-// Implementation note: tasks are posted bound to Unretained(this) to the I/O
-// thread and this is safe (even though the I/O thread is scoped to the renderer
-// process) because VideoCaptureImplManager only triggers deletion of its
-// VideoCaptureImpl's by calling DeInit which detours through the I/O thread, so
-// as long as nobody posts tasks after the DeInit() call is made, it is
-// guaranteed none of these Unretained posted tasks will dangle after the delete
-// goes through. The "as long as" is guaranteed by clients of
-// VideoCaptureImplManager not using devices after they've released
-// VideoCaptureHandle, which is a wrapper of this object.
+// Implementation note: tasks are posted bound to Unretained(this) to both the
+// I/O and Capture threads and this is safe (even though the I/O thread is
+// scoped to the renderer process and the capture_message_loop_proxy_ thread is
+// scoped to the VideoCaptureImplManager) because VideoCaptureImplManager only
+// triggers deletion of its VideoCaptureImpl's by calling DeInit which detours
+// through the capture & I/O threads, so as long as nobody posts tasks after the
+// DeInit() call is made, it is guaranteed none of these Unretained posted tasks
+// will dangle after the delete goes through.  The "as long as" is guaranteed by
+// clients of VideoCaptureImplManager not using devices after they've
+// RemoveDevice'd them.
 
 #ifndef CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_H_
 #define CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_H_
@@ -47,19 +49,6 @@
 class CONTENT_EXPORT VideoCaptureImpl
     : public media::VideoCapture, public VideoCaptureMessageFilter::Delegate {
  public:
-  VideoCaptureImpl(media::VideoCaptureSessionId session_id,
-                   VideoCaptureMessageFilter* filter);
-  virtual ~VideoCaptureImpl();
-
-  // Start listening to IPC messages.
-  void Init();
-
-  // Stop listening to IPC messages. Call |done_cb| when done.
-  void DeInit(base::Closure done_cb);
-
-  // Stop/resume delivering video frames to clients, based on flag |suspend|.
-  void SuspendCapture(bool suspend);
-
   // media::VideoCapture interface.
   virtual void StartCapture(
       media::VideoCapture::EventHandler* handler,
@@ -68,9 +57,23 @@
   virtual bool CaptureStarted() OVERRIDE;
   virtual int CaptureFrameRate() OVERRIDE;
 
-  media::VideoCaptureSessionId session_id() const { return session_id_; }
+  // VideoCaptureMessageFilter::Delegate interface.
+  virtual void OnBufferCreated(base::SharedMemoryHandle handle,
+                               int length,
+                               int buffer_id) OVERRIDE;
+  virtual void OnBufferDestroyed(int buffer_id) OVERRIDE;
+  virtual void OnBufferReceived(int buffer_id,
+                                base::TimeTicks timestamp,
+                                const media::VideoCaptureFormat& format)
+      OVERRIDE;
+  virtual void OnStateChanged(VideoCaptureState state) OVERRIDE;
+  virtual void OnDelegateAdded(int32 device_id) OVERRIDE;
 
+  // Stop/resume delivering video frames to clients, based on flag |suspend|.
+  virtual void SuspendCapture(bool suspend);
+
  private:
+  friend class VideoCaptureImplManager;
   friend class VideoCaptureImplTest;
   friend class MockVideoCaptureImpl;
 
@@ -78,35 +81,38 @@
   typedef std::map<media::VideoCapture::EventHandler*,
                    media::VideoCaptureParams> ClientInfo;
 
-  void InitOnIOThread();
-  void DeInitOnIOThread(base::Closure done_cb);
-  void SuspendCaptureOnIOThread(bool suspend);
-  void StartCaptureOnIOThread(
+  VideoCaptureImpl(media::VideoCaptureSessionId session_id,
+                   base::MessageLoopProxy* capture_message_loop_proxy,
+                   VideoCaptureMessageFilter* filter);
+  virtual ~VideoCaptureImpl();
+
+  void DoStartCaptureOnCaptureThread(
       media::VideoCapture::EventHandler* handler,
       const media::VideoCaptureParams& params);
-  void StopCaptureOnIOThread(media::VideoCapture::EventHandler* handler);
-
-  // VideoCaptureMessageFilter::Delegate interface.
-  virtual void OnBufferCreated(base::SharedMemoryHandle handle,
-                               int length,
-                               int buffer_id) OVERRIDE;
-  virtual void OnBufferDestroyed(int buffer_id) OVERRIDE;
-  virtual void OnBufferReceived(
+  void DoStopCaptureOnCaptureThread(media::VideoCapture::EventHandler* handler);
+  void DoBufferCreatedOnCaptureThread(base::SharedMemoryHandle handle,
+                                      int length,
+                                      int buffer_id);
+  void DoBufferDestroyedOnCaptureThread(int buffer_id);
+  void DoBufferReceivedOnCaptureThread(int buffer_id,
+                                       base::TimeTicks timestamp,
+                                       const media::VideoCaptureFormat& format);
+  void DoClientBufferFinishedOnCaptureThread(
       int buffer_id,
-      base::TimeTicks timestamp,
-      const media::VideoCaptureFormat& format) OVERRIDE;
-  virtual void OnStateChanged(VideoCaptureState state) OVERRIDE;
-  virtual void OnDelegateAdded(int32 device_id) OVERRIDE;
-
-  // Sends an IPC message to browser process when all clients are done with the
-  // buffer.
-  void OnClientBufferFinished(
-      int buffer_id,
       const scoped_refptr<ClientBuffer>& buffer);
+  void DoStateChangedOnCaptureThread(VideoCaptureState state);
+  void DoDelegateAddedOnCaptureThread(int32 device_id);
 
+  void DoSuspendCaptureOnCaptureThread(bool suspend);
+
+  void Init();
+  void DeInit(base::Closure task);
+  void DoDeInitOnCaptureThread(base::Closure task);
   void StopDevice();
   void RestartCapture();
   void StartCaptureInternal();
+  void AddDelegateOnIOThread();
+  void RemoveDelegateOnIOThread(base::Closure task);
   virtual void Send(IPC::Message* message);
 
   // Helpers.
@@ -114,6 +120,7 @@
                     ClientInfo* clients);
 
   const scoped_refptr<VideoCaptureMessageFilter> message_filter_;
+  const scoped_refptr<base::MessageLoopProxy> capture_message_loop_proxy_;
   const scoped_refptr<base::MessageLoopProxy> io_message_loop_proxy_;
   int device_id_;
   const int session_id_;
@@ -127,7 +134,7 @@
   ClientInfo clients_pending_on_restart_;
 
   // Member params_ represents the video format requested by the
-  // client to this class via StartCapture().
+  // client to this class via DoStartCaptureOnCaptureThread.
   media::VideoCaptureParams params_;
 
   // The device's video capture format sent from browser process side.