content: Cleanup class/struct forward declarations

content/child/notifications/notification_manager.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 CONTENT_CHILD_NOTIFICATIONS_NOTIFICATION_MANAGER_H_
 #define CONTENT_CHILD_NOTIFICATIONS_NOTIFICATION_MANAGER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
 #include <set>
 #include <unordered_map>
 #include <vector>
 
 #include "base/id_map.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "content/child/notifications/notification_dispatcher.h"
 #include "content/common/platform_notification_messages.h"
 #include "content/public/child/worker_thread.h"
 #include "third_party/WebKit/public/platform/modules/notifications/WebNotificationManager.h"
 #include "url/gurl.h"
 
 namespace content {
 
 struct NotificationResources;
-struct PlatformNotificationData;
 class ThreadSafeSender;
 
 class NotificationManager : public blink::WebNotificationManager,
                             public WorkerThread::Observer {
  public:
   ~NotificationManager() override;
 
   // |thread_safe_sender| and |notification_dispatcher| are used if
   // calling this leads to construction.
   static NotificationManager* ThreadSpecificInstance(
@@ skipping 67 matching lines @@
 
   // Map to store the delegate associated with a notification request Id.
   std::unordered_map<int, ActiveNotificationData> active_page_notifications_;
 
   DISALLOW_COPY_AND_ASSIGN(NotificationManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_NOTIFICATIONS_NOTIFICATION_MANAGER_H_