[Mac/Cleanup] Trim down Foundation.h and ApplicationServices.h includes

ios/web/net/cookie_notification_bridge.h

 // Copyright 2014 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 IOS_WEB_NET_COOKIE_NOTIFICATION_BRIDGE_H_
 #define IOS_WEB_NET_COOKIE_NOTIFICATION_BRIDGE_H_
 
 #include "base/mac/scoped_nsobject.h"
 #include "base/threading/thread_checker.h"
 
+@class NSNotification;
+
 namespace web {
 
 // CookieNotificationBridge listens to
 // NSHTTPCookieManagerCookiesChangedNotification on the main thread and re-sends
 // it to the cookie store on the IO thread.
 class CookieNotificationBridge {
  public:
   CookieNotificationBridge();
   ~CookieNotificationBridge();
 
  private:
   void OnNotificationReceived(NSNotification* notification);
   base::scoped_nsprotocol<id> observer_;
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(CookieNotificationBridge);
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_NET_COOKIE_NOTIFICATION_BRIDGE_H_