[Mac] Inform reference counted objects that hold a weak Browser* when the Browser is being destroye…

chrome/browser/ui/cocoa/toolbar/back_forward_menu_controller.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_TOOLBAR_BACK_FORWARD_MENU_CONTROLLER_H_
 #define CHROME_BROWSER_UI_COCOA_TOOLBAR_BACK_FORWARD_MENU_CONTROLLER_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/scoped_nsobject.h"
 #include "base/memory/scoped_ptr.h"
+#import "chrome/browser/ui/cocoa/has_weak_browser_pointer.h"
 #include "chrome/browser/ui/toolbar/back_forward_menu_model.h"
 
 @class MenuButton;
 
 typedef BackForwardMenuModel::ModelType BackForwardMenuType;
 const BackForwardMenuType BACK_FORWARD_MENU_TYPE_BACK =
     BackForwardMenuModel::BACKWARD_MENU;
 const BackForwardMenuType BACK_FORWARD_MENU_TYPE_FORWARD =
     BackForwardMenuModel::FORWARD_MENU;
 
 // A class that manages the back/forward menu (and delayed-menu button, and
 // model).
-
-@interface BackForwardMenuController : NSObject<NSMenuDelegate> {
+// Implement HasWeakBrowserPointer so we can clean up if the Browser is
+// destroyed.
+@interface BackForwardMenuController
+    : NSObject<NSMenuDelegate, HasWeakBrowserPointer> {
  @private
   BackForwardMenuType type_;
   MenuButton* button_;  // Weak; comes from nib.
   scoped_ptr<BackForwardMenuModel> model_;
   base::scoped_nsobject<NSMenu> backForwardMenu_;
 }
 
 // Type (back or forwards); can only be set on initialization.
 @property(readonly, nonatomic) BackForwardMenuType type;
 
 - (id)initWithBrowser:(Browser*)browser
             modelType:(BackForwardMenuType)type
                button:(MenuButton*)button;
 
 @end  // @interface BackForwardMenuController
 
 #endif  // CHROME_BROWSER_UI_COCOA_TOOLBAR_BACK_FORWARD_MENU_CONTROLLER_H_