Define frame subscription interface and implementation on Mac

content/port/browser/render_widget_host_view_port.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_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_PORT_H_
 #define CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_PORT_H_
 
 #include "base/callback.h"
 #include "base/process_util.h"
 #include "base/string16.h"
@@ skipping 24 matching lines @@
 struct WebPluginGeometry;
 }
 }
 
 namespace WebKit {
 struct WebScreenInfo;
 }
 
 namespace content {
 class BackingStore;
+class RenderWidgetHostViewFrameSubscriber;
 class SmoothScrollGesture;
 struct NativeWebKeyboardEvent;
 
 // This is the larger RenderWidgetHostView interface exposed only
 // within content/ and to embedders looking to port to new platforms.
 // RenderWidgetHostView class hierarchy described in render_widget_host_view.h.
 class CONTENT_EXPORT RenderWidgetHostViewPort : public RenderWidgetHostView {
  public:
   virtual ~RenderWidgetHostViewPort() {}
 
@@ skipping 126 matching lines @@
       const base::Callback<void(bool)>& callback) = 0;
 
   // Returns true if CopyFromCompositingSurfaceToVideoFrame() is likely to
   // succeed.
   //
   // TODO(nick): When VideoFrame copies are broadly implemented, this method
   // should be renamed to HasCompositingSurface(), or unified with
   // IsSurfaceAvailableForCopy() and HasAcceleratedSurface().
   virtual bool CanCopyToVideoFrame() const = 0;
 
+  // Return true if frame subscription is supported on this platform.
+  virtual bool CanSubscribeFrame() const { return false; }

[piman, 2013/02/22 20:45:47]

note: all methods in this class are pure virtual. You can move the default
implementations to RenderWidgetHostViewBase

[Alpha Left Google, 2013/02/22 21:05:38]

Okay will do.

+
+  // Begin subscribing for presentation events and captured frames.
+  // |subscriber| is now owned by this object, it will be called only on the
+  // UI thread.
+  //
+  // TODO(hclam): Implement this API on all platforms.
+  virtual void BeginFrameSubscription(
+      RenderWidgetHostViewFrameSubscriber* subscriber) {}
+
+  // End subscribing for frame presentation events. FrameSubscriber will be
+  // deleted after this call.
+  virtual void EndFrameSubscription() {}
+
   // Called when accelerated compositing state changes.
   virtual void OnAcceleratedCompositingStateChange() = 0;
   // |params.window| and |params.surface_id| indicate which accelerated
   // surface's buffers swapped. |params.renderer_id| and |params.route_id|
   // are used to formulate a reply to the GPU process to prevent it from getting
   // too far ahead. They may all be zero, in which case no flow control is
   // enforced; this case is currently used for accelerated plugins.
   virtual void AcceleratedSurfaceBuffersSwapped(
       const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params_in_pixel,
       int gpu_host_id) = 0;
@@ skipping 108 matching lines @@
   virtual BrowserAccessibilityManager*
       GetBrowserAccessibilityManager() const = 0;
   virtual void OnAccessibilityNotifications(
       const std::vector<AccessibilityHostMsg_NotificationParams>& params) {
   }
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_PORT_H_