Rename notification_id() to disambiguate its meaning

ui/message_center/notification.h

 // Copyright (c) 2013 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 UI_MESSAGE_CENTER_NOTIFICATION_H_
 #define UI_MESSAGE_CENTER_NOTIFICATION_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 48 matching lines @@
                const base::string16& title,
                const base::string16& message,
                const gfx::Image& icon,
                const base::string16& display_source,
                const NotifierId& notifier_id,
                const RichNotificationData& optional_fields,
                NotificationDelegate* delegate);
 
   Notification(const Notification& other);
 
-  Notification& operator=(const Notification& other);
-
   virtual ~Notification();
 
   // Copies the internal on-memory state from |base|, i.e. shown_as_popup,
   // is_read, and never_timeout.
   void CopyState(Notification* base);
 
   NotificationType type() const { return type_; }
   void set_type(NotificationType type) { type_ = type; }
 
   // Uniquely identifies a notification in the message center. For
@@ skipping 114 matching lines @@
   // will be invoked when the notification is clicked.
   static scoped_ptr<Notification> CreateSystemNotification(
       const std::string& notification_id,
       const base::string16& title,
       const base::string16& message,
       const gfx::Image& icon,
       const std::string& system_component_id,
       const base::Closure& click_callback);
 
  protected:
+  Notification& operator=(const Notification& other);
+
   // The type of notification we'd like displayed.
   NotificationType type_;
 
   std::string id_;
   base::string16 title_;
   base::string16 message_;
 
   // Image data for the associated icon, used by Ash when available.
   gfx::Image icon_;
 
   // The display string for the source of the notification.  Could be
   // the same as origin_url_, or the name of an extension.
   base::string16 display_source_;
 
  private:
   NotifierId notifier_id_;
   unsigned serial_number_;
   RichNotificationData optional_fields_;
   bool shown_as_popup_;  // True if this has been shown as a popup.
   bool is_read_;  // True if this has been seen in the message center.
 
   // A proxy object that allows access back to the JavaScript object that
   // represents the notification, for firing events.
   scoped_refptr<NotificationDelegate> delegate_;
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_NOTIFICATION_H_