chrome: Cleanup class/struct forward declarations

chrome/browser/ui/cocoa/confirm_bubble_cocoa.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 CHROME_BROWSER_UI_COCOA_CONFIRM_BUBBLE_COCOA_H_
 #define CHROME_BROWSER_UI_COCOA_CONFIRM_BUBBLE_COCOA_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/scoped_nsobject.h"
 
 @class ConfirmBubbleController;
-class ConfirmBubbleModel;
 
 // A view class that implements a bubble consisting of the following items:
 // * one icon ("icon")
 // * one title text ("title")
 // * one message text ("message")
 // * one optional link ("link")
 // * two optional buttons ("ok" and "cancel")
 //
 // This bubble is convenient when we wish to ask transient, non-blocking
 // questions. Unlike a dialog, a bubble menu disappears when we click outside of
@@ skipping 29 matching lines @@
 @end
 
 // Exposed only for unit testing.
 @interface ConfirmBubbleCocoa (ExposedForUnitTesting)
 - (void)clickOk;
 - (void)clickCancel;
 - (void)clickLink;
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_CONFIRM_BUBBLE_COCOA_H_