chrome: Cleanup class/struct forward declarations

chrome/browser/notifications/notification_platform_bridge_mac.h

 // Copyright 2015 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_NOTIFICATIONS_NOTIFICATION_PLATFORM_BRIDGE_MAC_H_
 #define CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_PLATFORM_BRIDGE_MAC_H_
 
 #include <set>
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/macros.h"
 #include "chrome/browser/notifications/alert_dispatcher_mac.h"
 #include "chrome/browser/notifications/notification_common.h"
 #include "chrome/browser/notifications/notification_platform_bridge.h"
 
 class Notification;
 @class NotificationCenterDelegate;
 @class NSDictionary;
 @class NSUserNotificationCenter;
 @class NSXPCConnection;
-class PrefService;
 
 // This class is an implementation of NotificationPlatformBridge that will
 // send platform notifications to the the MacOSX notification center.
 class NotificationPlatformBridgeMac : public NotificationPlatformBridge {
  public:
   NotificationPlatformBridgeMac(NSUserNotificationCenter* notification_center,
                                 id<AlertDispatcher> alert_dispatcher);
 
   ~NotificationPlatformBridgeMac() override;
 
@@ skipping 26 matching lines @@
   // this can be overriden in tests.
   base::scoped_nsobject<NSUserNotificationCenter> notification_center_;
 
   // The object in charge of dispatching remote notifications.
   base::scoped_nsprotocol<id<AlertDispatcher>> alert_dispatcher_;
 
   DISALLOW_COPY_AND_ASSIGN(NotificationPlatformBridgeMac);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_PLATFORM_BRIDGE_MAC_H_