Remove code only used by Mac single threaded compositing.

content/browser/renderer_host/render_widget_host_view_guest.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_GUEST_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_GUEST_H_
 
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 143 matching lines @@
   virtual void SetTakesFocusOnlyOnMouseDown(bool flag) OVERRIDE;
   virtual void SetWindowVisibility(bool visible) OVERRIDE;
   virtual void WindowFrameChanged() OVERRIDE;
   virtual void ShowDefinitionForSelection() OVERRIDE;
   virtual bool SupportsSpeech() const OVERRIDE;
   virtual void SpeakSelection() OVERRIDE;
   virtual bool IsSpeaking() const OVERRIDE;
   virtual void StopSpeaking() OVERRIDE;
 
   // RenderWidgetHostViewPort implementation.
-  virtual void AboutToWaitForBackingStoreMsg() OVERRIDE;
   virtual bool PostProcessEventForPluginIme(
       const NativeWebKeyboardEvent& event) OVERRIDE;
 #endif  // defined(OS_MACOSX)
 
 #if defined(OS_ANDROID)
   // RenderWidgetHostViewPort implementation.
   virtual void ShowDisambiguationPopup(const gfx::Rect& target_rect,
                                        const SkBitmap& zoomed_bitmap) OVERRIDE;
   virtual void HasTouchEventHandlers(bool need_touch_events) OVERRIDE;
 #endif  // defined(OS_ANDROID)
@@ skipping 42 matching lines @@
   RenderWidgetHostViewPort* platform_view_;
 #if defined(OS_WIN) || defined(USE_AURA)
   scoped_ptr<ui::GestureRecognizer> gesture_recognizer_;
 #endif  // defined(OS_WIN) || defined(USE_AURA)
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewGuest);
 };
 
 }  // namespace content
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_VIEW_GUEST_H_