Minimize the delegate dependencies for non persistent notifications.

chrome/browser/notifications/non_persistent_notification_handler.h

 // Copyright 2016 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_NON_PERSISTENT_NOTIFICATION_HANDLER_H_
 #define CHROME_BROWSER_NOTIFICATIONS_NON_PERSISTENT_NOTIFICATION_HANDLER_H_
 
-#include <unordered_map>
-
 #include "base/macros.h"
-#include "base/memory/ref_counted.h"
 #include "chrome/browser/notifications/notification_handler.h"
 
-class NotificationDelegate;
-
 // NotificationHandler implementation for non persistent notifications.
 class NonPersistentNotificationHandler : public NotificationHandler {
  public:
   NonPersistentNotificationHandler();
   ~NonPersistentNotificationHandler() override;
 
   // NotificationHandler implementation
   void OnClose(Profile* profile,
                const std::string& origin,
                const std::string& notification_id,
                bool by_user) override;
 
   void OnClick(Profile* profile,
                const std::string& origin,
                const std::string& notification_id,
                int action_index,
                const base::NullableString16& reply) override;
 
   void OpenSettings(Profile* profile) override;
 
-  void RegisterNotification(const std::string& notification_id,
-                            NotificationDelegate* delegate) override;
-
  private:
-  // map of delegate objects keyed by notification id.
-  std::unordered_map<std::string, scoped_refptr<NotificationDelegate>>
-      notifications_;
-
   DISALLOW_COPY_AND_ASSIGN(NonPersistentNotificationHandler);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_NON_PERSISTENT_NOTIFICATION_HANDLER_H_