Add the "virtual" keyword on method overrides that are missing it.

chrome/browser/browsing_data_remover.h

 // Copyright (c) 2010 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_BROWSING_DATA_REMOVER_H_
 #define CHROME_BROWSER_BROWSING_DATA_REMOVER_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 79 matching lines @@
 
   // BrowsingDataRemover deletes itself (using DeleteTask) and is not supposed
   // to be deleted by other objects so make destructor private and DeleteTask
   // a friend.
   friend class DeleteTask<BrowsingDataRemover>;
   ~BrowsingDataRemover();
 
   // NotificationObserver method. Callback when TemplateURLModel has finished
   // loading. Deletes the entries from the model, and if we're not waiting on
   // anything else notifies observers and deletes this BrowsingDataRemover.
-  void Observe(NotificationType type,
-               const NotificationSource& source,
-               const NotificationDetails& details);
+  virtual void Observe(NotificationType type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details);
 
   // If we're not waiting on anything, notifies observers and deletes this
   // object.
   void NotifyAndDeleteIfDone();
 
   // Callback when the cache has been deleted. Invokes NotifyAndDeleteIfDone.
   void ClearedCache();
 
   // Invoked on the IO thread to delete from the cache.
   void ClearCacheOnIOThread();
@@ skipping 76 matching lines @@
 
   ObserverList<Observer> observer_list_;
 
   // Used if we need to clear history.
   CancelableRequestConsumer request_consumer_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowsingDataRemover);
 };
 
 #endif  // CHROME_BROWSER_BROWSING_DATA_REMOVER_H_