Refactor how surfaces are acquired for GPU compositing.

chrome/browser/renderer_host/render_widget_host_view_mac.mm

 // 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.
 
 #include <QuartzCore/QuartzCore.h>
 
 #include "chrome/browser/renderer_host/render_widget_host_view_mac.h"
 
 #include "app/app_switches.h"
 #include "app/surface/io_surface_support_mac.h"
@@ skipping 1229 matching lines @@
 void RenderWidgetHostViewMac::GpuRenderingStateDidChange() {
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (GetRenderWidgetHost()->is_accelerated_compositing_active()) {
     UpdateRootGpuViewVisibility(
         GetRenderWidgetHost()->is_accelerated_compositing_active());
   } else {
     needs_gpu_visibility_update_after_repaint_ = true;
   }
 }
 
+gfx::PluginWindowHandle RenderWidgetHostViewMac::AcquireCompositingSurface() {
+  return AllocateFakePluginWindowHandle(/*opaque=*/true, /*root=*/true);
+}
+
+void RenderWidgetHostViewMac::ReleaseCompositingSurface(
+    gfx::PluginWindowHandle surface) {
+  DestroyFakePluginWindowHandle(surface);
+}
+
 void RenderWidgetHostViewMac::DrawAcceleratedSurfaceInstance(
       CGLContextObj context,
       gfx::PluginWindowHandle plugin_handle,
       NSSize size) {
   // Called on the display link thread.
   CGLSetCurrentContext(context);
 
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   // Note that we place the origin at the upper left corner with +y
@@ skipping 1566 matching lines @@
   if (!string) return NO;
 
   // If the user is currently using an IME, confirm the IME input,
   // and then insert the text from the service, the same as TextEdit and Safari.
   [self confirmComposition];
   [self insertText:string];
   return YES;
 }
 
 @end