Use webrtc::DesktopCapturer for screen capturer implementation.

media/video/capture/screen/screen_capturer.h

Index: media/video/capture/screen/screen_capturer.h
diff --git a/media/video/capture/screen/screen_capturer.h b/media/video/capture/screen/screen_capturer.h
index bc3d454e945971b618a25ae8c753c120d7a3d911..3ba1fa4de24a5bf07a9a22c79a432de762a7ad87 100644
--- a/media/video/capture/screen/screen_capturer.h
+++ b/media/video/capture/screen/screen_capturer.h
@@ -8,15 +8,12 @@
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
-#include "base/shared_memory.h"
 #include "media/base/media_export.h"
-#include "media/video/capture/screen/shared_buffer.h"
+#include "third_party/webrtc/modules/desktop_capture/desktop_capturer.h"
 
 namespace media {
 
-class ScreenCaptureData;
 struct MouseCursorShape;
-class SharedBuffer;
 
 // Class used to capture video frames asynchronously.
 //
@@ -36,32 +33,19 @@ class SharedBuffer;
 // Implementation has to ensure the following guarantees:
 // 1. Double buffering
 //    Since data can be read while another capture action is happening.
-class MEDIA_EXPORT ScreenCapturer {
+class MEDIA_EXPORT ScreenCapturer : public webrtc::DesktopCapturer {
  public:
   // Provides callbacks used by the capturer to pass captured video frames and
   // mouse cursor shapes to the processing pipeline.
-  class MEDIA_EXPORT Delegate {
+    // TODO(sergeyu): Move cursor shape capturing to a separate class.

[alexeypa (please no reviews), 2013/04/26 21:33:58]

nit: Indentation. Also add a brief explanation why it is better to be a separate
interface.

One can argue that the mouse cursor is a part of the capture frame so it has to
be synchronized with the frame itself. Or embedded in the frame. But sending the
cursor shape updates asynchronously from video and with a higher priority will
result in better perceived responsiveness.

[Sergey Ulanov, 2013/05/07 22:25:50]

Done.
These are good points, but let's discuss it later - this TODO was here before, I
just moved it here from OnCursorShapeChanged().

+  class MEDIA_EXPORT MouseShapeObserver {
    public:
-    // Creates a shared memory buffer of the given size. Returns NULL if shared
-    // buffers are not supported.
-    virtual scoped_refptr<SharedBuffer> CreateSharedBuffer(uint32 size);
-
-    // Notifies the delegate that the buffer is no longer used and can be
-    // released.
-    virtual void ReleaseSharedBuffer(scoped_refptr<SharedBuffer> buffer);
-
-    // Called when a video frame has been captured. |capture_data| describes
-    // a captured frame.
-    virtual void OnCaptureCompleted(
-        scoped_refptr<ScreenCaptureData> capture_data) = 0;
-
     // Called when the cursor shape has changed.
-    // TODO(sergeyu): Move cursor shape capturing to a separate class.
     virtual void OnCursorShapeChanged(
         scoped_ptr<MouseCursorShape> cursor_shape) = 0;
 
    protected:
-    virtual ~Delegate() {}
+    virtual ~MouseShapeObserver() {}
   };
 
   virtual ~ScreenCapturer() {}
@@ -79,18 +63,10 @@ class MEDIA_EXPORT ScreenCapturer {
   static scoped_ptr<ScreenCapturer> CreateWithDisableAero(bool disable_aero);
 #endif

[alexeypa (please no reviews), 2013/04/26 21:33:58]

nit: add // defined(OS_WIN)

[Sergey Ulanov, 2013/05/07 22:25:50]

Done.

 
-  // Called at the beginning of a capturing session. |delegate| must remain
-  // valid until Stop() is called.
-  virtual void Start(Delegate* delegate) = 0;
-
-  // Captures the screen data associated with each of the accumulated
-  // dirty region. When the capture is complete, the delegate is notified even
-  // if the dirty region is empty.
-  //
-  // It is OK to call this method while another thread is reading
-  // data of the previous capture. There can be at most one concurrent read
-  // going on when this method is called.
-  virtual void CaptureFrame() = 0;
+  // Called at the beginning of a capturing session. |mouse_shape_observer| must
+  // remain valid until the capturer is destroyed.
+  virtual void SetMouseShapeObserver(
+      MouseShapeObserver* mouse_shape_observer) = 0;
 };
 
 }  // namespace media