Standardize usage of virtual/override/final in ui/

ui/message_center/cocoa/popup_collection.mm

 // 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.
 
 #import "ui/message_center/cocoa/popup_collection.h"
 
 #import "ui/message_center/cocoa/notification_controller.h"
 #import "ui/message_center/cocoa/popup_controller.h"
 #include "ui/message_center/message_center.h"
 #include "ui/message_center/message_center_observer.h"
@@ skipping 39 matching lines @@
 
 class PopupCollectionObserver : public message_center::MessageCenterObserver {
  public:
   PopupCollectionObserver(message_center::MessageCenter* message_center,
                           MCPopupCollection* popup_collection)
       : message_center_(message_center),
         popup_collection_(popup_collection) {
     message_center_->AddObserver(this);
   }
 
-  virtual ~PopupCollectionObserver() {
-    message_center_->RemoveObserver(this);
-  }
+  ~PopupCollectionObserver() override { message_center_->RemoveObserver(this); }
 
-  virtual void OnNotificationAdded(
-      const std::string& notification_id) override {
+  void OnNotificationAdded(const std::string& notification_id) override {
     [popup_collection_ layoutNewNotifications];
   }
 
-  virtual void OnNotificationRemoved(const std::string& notification_id,
-                                     bool user_id) override {
+  void OnNotificationRemoved(const std::string& notification_id,
+                             bool user_id) override {
     [popup_collection_ removeNotification:notification_id];
   }
 
-  virtual void OnNotificationUpdated(
-      const std::string& notification_id) override {
+  void OnNotificationUpdated(const std::string& notification_id) override {
     [popup_collection_ updateNotification:notification_id];
   }
 
  private:
   message_center::MessageCenter* message_center_;  // Weak, global.
 
   MCPopupCollection* popup_collection_;  // Weak, owns this.
 };
 
 }  // namespace
@@ skipping 307 matching lines @@
   }
 
   pendingUpdateNotificationIDs_.clear();
 
   // Start re-layout of all notifications, so that it readjusts the Y origin of
   // all updated popups and any popups that come below them.
   [self layoutNotifications];
 }
 
 @end