Eliminate video capture thread in renderer

content/renderer/media/video_capture_impl.h

Index: content/renderer/media/video_capture_impl.h
diff --git a/content/renderer/media/video_capture_impl.h b/content/renderer/media/video_capture_impl.h
index 2215cef4336456920329f98ab0c500decbee8f12..ba0e6521a07845ac8f82b2c449619c7a4f93854e 100644
--- a/content/renderer/media/video_capture_impl.h
+++ b/content/renderer/media/video_capture_impl.h
@@ -12,20 +12,20 @@
 
 // The media::VideoCapture and VideoCaptureMessageFilter::Delegate are
 // asynchronous interfaces, which means callers can call those interfaces

[Ami GONE FROM CHROMIUM, 2014/01/08 01:43:58]

"async interface" doesn't usually mean "call on any thread", so this sentence is
tortured.

-// 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.
+// from any threads without worrying about thread safety. Public methods of

[Ami GONE FROM CHROMIUM, 2014/01/08 01:43:58]

s/any threads/any thread/

[Alpha Left Google, 2014/01/08 22:30:50]

Done.

+// VideoCaptureImpl can be called on any threads. Internally it runs on

[Ami GONE FROM CHROMIUM, 2014/01/08 01:43:58]

ditto

[Ami GONE FROM CHROMIUM, 2014/01/08 01:43:58]

s/it runs/they run/

[Alpha Left Google, 2014/01/08 22:30:50]

Done.

+// the IO thread. Client of this class implements interface

[Ami GONE FROM CHROMIUM, 2014/01/08 01:43:58]

Client...implements 
->
Clients...implement

[Alpha Left Google, 2014/01/08 22:30:50]

Done.

+// media::VideoCapture::EventHandler which is called only on the IO thread.
 //
-// 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.
+// 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.
 
 #ifndef CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_H_
 #define CONTENT_RENDERER_MEDIA_VIDEO_CAPTURE_IMPL_H_
@@ -49,6 +49,19 @@ namespace content {
 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,
@@ -57,23 +70,9 @@ class CONTENT_EXPORT VideoCaptureImpl
   virtual bool CaptureStarted() OVERRIDE;
   virtual int CaptureFrameRate() OVERRIDE;
 
-  // 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::Time 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);
+  media::VideoCaptureSessionId session_id() const { return session_id_; }
 
  private:
-  friend class VideoCaptureImplManager;
   friend class VideoCaptureImplTest;
   friend class MockVideoCaptureImpl;
 
@@ -81,39 +80,35 @@ class CONTENT_EXPORT VideoCaptureImpl
   typedef std::map<media::VideoCapture::EventHandler*,
                    media::VideoCaptureParams> ClientInfo;
 
-  VideoCaptureImpl(media::VideoCaptureSessionId session_id,
-                   base::MessageLoopProxy* capture_message_loop_proxy,
-                   VideoCaptureMessageFilter* filter);
-  virtual ~VideoCaptureImpl();
-
-  void DoStartCaptureOnCaptureThread(
+  void InitOnIOThread();
+  void DeInitOnIOThread(base::Closure done_cb);
+  void SuspendCaptureOnIOThread(bool suspend);
+  void StartCaptureOnIOThread(
       media::VideoCapture::EventHandler* handler,
       const media::VideoCaptureParams& params);
-  void DoStopCaptureOnCaptureThread(media::VideoCapture::EventHandler* handler);
-  void DoBufferCreatedOnCaptureThread(base::SharedMemoryHandle handle,
-                                      int length,
-                                      int buffer_id);
-  void DoBufferDestroyedOnCaptureThread(int buffer_id);
-  void DoBufferReceivedOnCaptureThread(
+  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(
       int buffer_id,
       base::Time timestamp,
-      const media::VideoCaptureFormat& format);
-  void DoClientBufferFinishedOnCaptureThread(
+      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.
@@ -121,7 +116,6 @@ class CONTENT_EXPORT VideoCaptureImpl
                     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_;
@@ -135,7 +129,7 @@ class CONTENT_EXPORT VideoCaptureImpl
   ClientInfo clients_pending_on_restart_;
 
   // Member params_ represents the video format requested by the
-  // client to this class via DoStartCaptureOnCaptureThread.
+  // client to this class via StartCapture().
   media::VideoCaptureParams params_;
 
   // The device's video capture format sent from browser process side.