Re-factor Ash Message Center code part 4/4

ash/system/web_notification/web_notification_list.h

 // Copyright (c) 2012 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 ASH_SYSTEM_WEB_NOTIFICATION_WEB_NOTIFICATION_LIST_H_
 #define ASH_SYSTEM_WEB_NOTIFICATION_WEB_NOTIFICATION_LIST_H_
 
 #include <list>
 #include <string>
 
@@ skipping 26 matching lines @@
     // Called when a notification is clicked on.
     virtual void OnNotificationClicked(const std::string& id) = 0;
 
     // Returns the list of notifications to display.
     virtual WebNotificationList* GetNotificationList() = 0;
   };
 
   explicit WebNotificationList(Delegate* delegate);
   virtual ~WebNotificationList();
 
+  // Affects whether or not a message has been "read".
   void SetMessageCenterVisible(bool visible);
 
   void AddNotification(const std::string& id,
                        const string16& title,
                        const string16& message,
                        const string16& display_source,
                        const std::string& extension_id);
 
   void UpdateNotificationMessage(const std::string& old_id,
                                  const std::string& new_id,
@@ skipping 20 matching lines @@
   bool HasPopupNotifications();
 
   // Modifies |notifications| to contain the |kMaxVisiblePopupNotifications|
   // least recent notifications that have not been shown as a popup.
   void GetPopupNotifications(Notifications* notifications);
 
   // Marks the popups returned by GetPopupNotifications() as shown.
   void MarkPopupsAsShown();
 
   const Notifications& notifications() const { return notifications_; }
-  int unread_count() const { return unread_count_; }
+  size_t unread_count() const { return unread_count_; }
 
   static const size_t kMaxVisiblePopupNotifications;
   static const size_t kMaxVisibleMessageCenterNotifications;
 
  private:
   // Iterates through the list and returns the first notification matching |id|
   // (should always be unique).
   Notifications::iterator GetNotification(const std::string& id);
 
   void EraseNotification(Notifications::iterator iter);
 
   void PushNotification(WebNotification& notification);
 
   // Returns the |kMaxVisiblePopupNotifications| least recent notifications
   // that have not been shown as a popup.
   void GetPopupIterators(Notifications::iterator& first,
                          Notifications::iterator& last);
 
   Delegate* delegate_;
   Notifications notifications_;
   bool message_center_visible_;
-  int unread_count_;
+  size_t unread_count_;
 
   DISALLOW_COPY_AND_ASSIGN(WebNotificationList);
 };
 
 }  // namespace message_center
 
 #endif // ASH_SYSTEM_WEB_NOTIFICATION_WEB_NOTIFICATION_LIST_H_