AcceleratorProvider: Make GetAcceleratorForCommandId const.

ui/views/controls/textfield/textfield.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_VIEWS_CONTROLS_TEXTFIELD_TEXTFIELD_H_
 #define UI_VIEWS_CONTROLS_TEXTFIELD_TEXTFIELD_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 254 matching lines @@
   void ConvertPointToScreen(gfx::Point* point) override;
   void ConvertPointFromScreen(gfx::Point* point) override;
   bool DrawsHandles() override;
   void OpenContextMenu(const gfx::Point& anchor) override;
   void DestroyTouchSelection() override;
 
   // ui::SimpleMenuModel::Delegate overrides:
   bool IsCommandIdChecked(int command_id) const override;
   bool IsCommandIdEnabled(int command_id) const override;
   bool GetAcceleratorForCommandId(int command_id,
-                                  ui::Accelerator* accelerator) override;
+                                  ui::Accelerator* accelerator) const override;
   void ExecuteCommand(int command_id, int event_flags) override;
 
   // ui::TextInputClient overrides:
   void SetCompositionText(const ui::CompositionText& composition) override;
   void ConfirmCompositionText() override;
   void ClearCompositionText() override;
   void InsertText(const base::string16& text) override;
   void InsertChar(const ui::KeyEvent& event) override;
   ui::TextInputType GetTextInputType() const override;
   ui::TextInputMode GetTextInputMode() const override;
@@ skipping 198 matching lines @@
 
   // Used to bind callback functions to this object.
   base::WeakPtrFactory<Textfield> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Textfield);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_TEXTFIELD_TEXTFIELD_H_