Removes SimpleMenuModel::FlipIndex. It was only used by

chrome/browser/ui/views/frame/system_menu_model.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 CHROME_BROWSER_UI_VIEWS_FRAME_SYSTEM_MENU_MODEL_H_
 #define CHROME_BROWSER_UI_VIEWS_FRAME_SYSTEM_MENU_MODEL_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ui/base/models/simple_menu_model.h"
 
 // A SimpleMenuModel subclass that allows the system menu for a window to be
 // wrapped.
 class SystemMenuModel : public ui::SimpleMenuModel {
  public:
   explicit SystemMenuModel(ui::SimpleMenuModel::Delegate* delegate);
   virtual ~SystemMenuModel();
 
   // Overridden from ui::MenuModel:
   virtual int GetFirstItemIndex(gfx::NativeMenu native_menu) const OVERRIDE;
 
- protected:
-  // Overridden from ui::SimpleMenuModel:
-  virtual int FlipIndex(int index) const OVERRIDE;
-
  private:
   DISALLOW_COPY_AND_ASSIGN(SystemMenuModel);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_FRAME_SYSTEM_MENU_MODEL_H_