Removes SimpleMenuModel::FlipIndex. It was only used by

ui/base/models/simple_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 UI_BASE_MODELS_SIMPLE_MENU_MODEL_H_
 #define UI_BASE_MODELS_SIMPLE_MENU_MODEL_H_
 
 #include <vector>
 
 #include "base/memory/weak_ptr.h"
@@ skipping 124 matching lines @@
   virtual void ActivatedAt(int index) OVERRIDE;
   virtual void ActivatedAt(int index, int event_flags) OVERRIDE;
   virtual MenuModel* GetSubmenuModelAt(int index) const OVERRIDE;
   virtual void MenuWillShow() OVERRIDE;
   virtual void MenuClosed() OVERRIDE;
   virtual void SetMenuModelDelegate(
       ui::MenuModelDelegate* menu_model_delegate) OVERRIDE;
   virtual MenuModelDelegate* GetMenuModelDelegate() const OVERRIDE;
 
  protected:
-  // Some variants of this model (SystemMenuModel) relies on items to be
-  // inserted backwards. This is counter-intuitive for the API, so rather than
-  // forcing customers to insert things backwards, we return the indices
-  // backwards instead. That's what this method is for. By default, it just
-  // returns what it's passed.
-  virtual int FlipIndex(int index) const;
-
   void set_delegate(Delegate* delegate) { delegate_ = delegate; }
   Delegate* delegate() { return delegate_; }
 
  private:
   struct Item;
 
   typedef std::vector<Item> ItemVector;
 
-  // Caller needs to call FlipIndex() if necessary. Returns |index|.
+  // Returns |index|.
   int ValidateItemIndex(int index) const;
 
   // Functions for inserting items into |items_|.
   void AppendItem(const Item& item);
   void InsertItemAtIndex(const Item& item, int index);
   void ValidateItem(const Item& item);
 
   // Notify the delegate that the menu is closed.
   void OnMenuClosed();
 
   ItemVector items_;
 
   Delegate* delegate_;
 
   MenuModelDelegate* menu_model_delegate_;
 
   base::WeakPtrFactory<SimpleMenuModel> method_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SimpleMenuModel);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_MODELS_SIMPLE_MENU_MODEL_H_