Add IPC allowing GPU process to tell browser process to temporarily drop a front buffer.

content/browser/renderer_host/render_widget_host_view.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_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_H_
 #pragma once
 
 #if defined(OS_MACOSX)
 #include <OpenGL/OpenGL.h>
@@ skipping 206 matching lines @@
   // enforced; this case is currently used for accelerated plugins.
   virtual void AcceleratedSurfaceBuffersSwapped(
       const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params,
       int gpu_host_id) = 0;
   // Similar to above, except |params.(x|y|width|height)| define the region
   // of the surface that changed.
   virtual void AcceleratedSurfacePostSubBuffer(
       const GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params& params,
       int gpu_host_id) = 0;
 
+  // Release the accelerated surface temporarily. It will be recreated on the
+  // next swap buffers or post sub buffer.
+  virtual void AcceleratedSurfaceSuspend() = 0;
+
 #if defined(OS_MACOSX)
   // Tells the view whether or not to accept first responder status.  If |flag|
   // is true, the view does not accept first responder status and instead
   // manually becomes first responder when it receives a mouse down event.  If
   // |flag| is false, the view participates in the key-view chain as normal.
   virtual void SetTakesFocusOnlyOnMouseDown(bool flag) = 0;
 
   // Retrieve the bounds of the view, in cocoa view coordinates.
   // If the UI scale factor is 2, |GetViewBounds()| will return a size of e.g.
   // (400, 300) in pixels, while this method will return (200, 150).
@@ skipping 136 matching lines @@
   ui::Range selection_range_;
 
  private:
   // Manager of the tree representation of the WebKit render tree.
   scoped_ptr<BrowserAccessibilityManager> browser_accessibility_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostView);
 };
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_H_