Make //content responsible for generating notification Ids

chrome/browser/notifications/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_PERSISTENT_NOTIFICATION_HANDLER_H_
 #define CHROME_BROWSER_NOTIFICATIONS_PERSISTENT_NOTIFICATION_HANDLER_H_
 
 #include "base/macros.h"
 #include "chrome/browser/notifications/notification_handler.h"
 
 class NotificationDelegate;
 
 // NotificationHandler implementation for persistent, service worker backed,
 // notifications.
 class PersistentNotificationHandler : public NotificationHandler {
  public:
   PersistentNotificationHandler();
   ~PersistentNotificationHandler() override;
 
-  // NotificationHandler implementation
+  // 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) override;
-
   void OpenSettings(Profile* profile) override;
-
   void RegisterNotification(const std::string& notification_id,
                             NotificationDelegate* delegate) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PersistentNotificationHandler);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_PERSISTENT_NOTIFICATION_HANDLER_H_