Mac gpu: on gpu<->nongpu transitions, make sure to not show uninitialized memory

chrome/browser/renderer_host/accelerated_surface_container_manager_mac.h

 // Copyright (c) 2010 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 CHROME_BROWSER_RENDERER_HOST_GPU_PLUGIN_CONTAINER_MANAGER_MAC_H_
 #define CHROME_BROWSER_RENDERER_HOST_GPU_PLUGIN_CONTAINER_MANAGER_MAC_H_
 #pragma once
 
 #include <OpenGL/OpenGL.h>
 #include <map>
@@ skipping 28 matching lines @@
   // contains the compositor's output.
   bool IsRootContainer(gfx::PluginWindowHandle id) const;
 
   // Returns the handle of the compositor surface, or kNullPluginWindow if no
   // compositor surface is active.
   gfx::PluginWindowHandle root_container_handle() const {
     return root_container_handle_;
   }
 
   // Informs the manager if gpu rendering is active.
-  void set_gpu_rendering_active(bool active) { gpu_rendering_active_ = active; }
+  void set_gpu_rendering_active(bool active);
 
   // Sets the size and backing store of the plugin instance.  There are two
   // versions: the IOSurface version is used on systems where the IOSurface
   // API is supported (Mac OS X 10.6 and later); the TransportDIB is used on
   // Mac OS X 10.5 and earlier.
   void SetSizeAndIOSurface(gfx::PluginWindowHandle id,
                            int32 width,
                            int32 height,
                            uint64 io_surface_identifier);
   void SetSizeAndTransportDIB(gfx::PluginWindowHandle id,
                               int32 width,
                               int32 height,
                               TransportDIB::Handle transport_dib);
 
   // Takes an update from WebKit about a plugin's position and size and moves
   // the plugin accordingly.
   void SetPluginContainerGeometry(const webkit_glue::WebPluginGeometry& move);
 
   // Draws the plugin container associated with the given id into the given
   // OpenGL context, which must already be current.
   void Draw(CGLContextObj context, gfx::PluginWindowHandle id);
 
   // Causes the next Draw call on each container to trigger a texture upload.
   // Should be called any time the drawing context has changed.
   void ForceTextureReload();
 
   // Notifies a surface that it has been painted to.
   void SetSurfaceWasPaintedTo(gfx::PluginWindowHandle id, uint64 surface_id);
 
+  // Notifies the root container that its surface is invalid.
+  void SetRootSurfaceInvalid();
+
   // Returns if a given surface should be shown.
   bool SurfaceShouldBeVisible(gfx::PluginWindowHandle id) const;
  private:
   uint32 current_id_;
 
   // Maps a "fake" plugin window handle to the corresponding container.
   AcceleratedSurfaceContainerMac*
       MapIDToContainer(gfx::PluginWindowHandle id) const;
 
   // A map that associates plugin window handles with their containers.
@@ skipping 21 matching lines @@
   // Both |plugin_window_to_container_map_| and the
   // AcceleratedSurfaceContainerMac in it are not threadsafe, but accessed from
   // multiple threads. All these accesses are guarded by this lock.
   mutable Lock lock_;
 
   DISALLOW_COPY_AND_ASSIGN(AcceleratedSurfaceContainerManagerMac);
 };
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_GPU_PLUGIN_CONTAINER_MANAGER_MAC_H_