MacViews: Get views based toolbar to compile on the Mac.

chrome/browser/ui/cocoa/toolbar/toolbar_button.h

-// Copyright (c) 2011 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_COCOA_TOOLBAR_TOOLBAR_BUTTON_H_
-#define CHROME_BROWSER_UI_COCOA_TOOLBAR_TOOLBAR_BUTTON_H_
-
-#import <Cocoa/Cocoa.h>
-
-// NSButton subclass which handles middle mouse clicking.
-
-@interface ToolbarButton : NSButton {
- @protected
-  // YES when middle mouse clicks should be handled.
-  BOOL handleMiddleClick_;
-}
-
-// Whether or not to handle the mouse middle click events.
-@property(assign, nonatomic) BOOL handleMiddleClick;
-
-@end
-
-@interface ToolbarButton (ExposedForTesting)
-- (BOOL)shouldHandleEvent:(NSEvent*)theEvent;
-@end
-
-#endif  // CHROME_BROWSER_UI_COCOA_TOOLBAR_TOOLBAR_BUTTON_H_