Fix compiler warnings.

chrome/browser/chromeos/status/power_menu_button.h

 // Copyright (c) 2006-2008 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_CHROMEOS_STATUS_POWER_MENU_BUTTON_H_
 #define CHROME_BROWSER_CHROMEOS_STATUS_POWER_MENU_BUTTON_H_
 
 #include "app/menus/menu_model.h"
 #include "chrome/browser/chromeos/cros/power_library.h"
 #include "chrome/browser/chromeos/status/status_area_button.h"
@@ skipping 28 matching lines @@
   virtual bool GetIconAt(int index, SkBitmap* icon) const { return false; }
   virtual bool IsEnabledAt(int index) const { return false; }
   virtual menus::MenuModel* GetSubmenuModelAt(int index) const { return NULL; }
   virtual void HighlightChangedTo(int index) {}
   virtual void ActivatedAt(int index) {}
   virtual void MenuWillShow() {}
 
   // PowerLibrary::Observer implementation.
   virtual void PowerChanged(PowerLibrary* obj);
 
-  const int icon_id() const { return icon_id_; }
+  int icon_id() const { return icon_id_; }
 
  protected:
   // StatusAreaButton implementation.
   virtual void DrawPressed(gfx::Canvas* canvas);
   virtual void DrawIcon(gfx::Canvas* canvas);
 
  private:
   // views::ViewMenuDelegate implementation.
   virtual void RunMenu(views::View* source, const gfx::Point& pt);
 
@@ skipping 11 matching lines @@
 
   // The currently showing icon bitmap id.
   int icon_id_;
 
   DISALLOW_COPY_AND_ASSIGN(PowerMenuButton);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_STATUS_POWER_MENU_BUTTON_H_