Define frame subscription interface and implementation on Mac

content/browser/renderer_host/render_widget_host_view_base.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_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_
 
 #if defined(OS_MACOSX)
 #include <OpenGL/OpenGL.h>
 #endif
@@ skipping 49 matching lines @@
       const WebKit::WebMouseWheelEvent& event) OVERRIDE;
   virtual void SetPopupType(WebKit::WebPopupType popup_type) OVERRIDE;
   virtual WebKit::WebPopupType GetPopupType() OVERRIDE;
   virtual BrowserAccessibilityManager*
       GetBrowserAccessibilityManager() const OVERRIDE;
   virtual void ProcessAckedTouchEvent(const WebKit::WebTouchEvent& touch,
                                       InputEventAckState ack_result) OVERRIDE;
   virtual SmoothScrollGesture* CreateSmoothScrollGesture(
       bool scroll_down, int pixels_to_scroll, int mouse_event_x,
       int mouse_event_y) OVERRIDE;
+  virtual bool CanSubscribeFrame() const OVERRIDE;
+  virtual void BeginFrameSubscription(
+      RenderWidgetHostViewFrameSubscriber* subscriber) OVERRIDE;
+  virtual void EndFrameSubscription() OVERRIDE;
   virtual void OnSwapCompositorFrame(
       const cc::CompositorFrame& frame) OVERRIDE {}
 
   void SetBrowserAccessibilityManager(BrowserAccessibilityManager* manager);
 
   // Notification that a resize or move session ended on the native widget.
   void UpdateScreenInfo(gfx::NativeView view);
 
 #if defined(OS_WIN)
   // The callback that DetachPluginsHelper calls for each child window. Call
@@ skipping 54 matching lines @@
 
   gfx::Rect current_display_area_;
   float current_device_scale_factor_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewBase);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_BASE_H_