[Mac]Implement ViewID support.

chrome/browser/cocoa/menu_button.h

 // Copyright (c) 2009 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_COCOA_MENU_BUTTON_H_
 #define CHROME_BROWSER_COCOA_MENU_BUTTON_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/scoped_nsobject.h"
+#import "chrome/browser/cocoa/button_with_viewid.h"
 
 // This a button which displays a user-provided menu "attached" below it upon
 // being clicked or dragged (or clicked and held). It expects a
 // |ClickHoldButtonCell| as cell.
-@interface MenuButton : NSButton {
+@interface MenuButton : ButtonWithViewID {
  @private
   IBOutlet NSMenu* attachedMenu_;
   scoped_nsobject<NSPopUpButtonCell> popUpCell_;
 }
 
 // The menu to display. Note that it should have no (i.e., a blank) title and
 // that the 0-th entry should be blank (and won't be displayed). (This is
 // because we use a pulldown list, for which Cocoa uses the 0-th item as "title"
 // in the button. This might change if we ever switch to a pop-up. Our direct
 // use of the given NSMenu object means that the one can set and use NSMenu's
 // delegate as usual.)
 @property(assign, nonatomic) NSMenu* attachedMenu;
 
 @end  // @interface MenuButton
 
 #endif  // CHROME_BROWSER_COCOA_MENU_BUTTON_H_