Virtual destructors should have virtual keyword.

chrome/browser/extensions/user_script_listener.h

 // Copyright (c) 2011 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_EXTENSIONS_USER_SCRIPT_LISTENER_H_
 #define CHROME_BROWSER_EXTENSIONS_USER_SCRIPT_LISTENER_H_
 #pragma once
 
 #include <list>
 
@@ skipping 31 matching lines @@
       net::URLRequest* request,
       const ResourceDispatcherHostRequestInfo& request_info,
       const GlobalRequestID& request_id);
   virtual void WillShutdownResourceQueue();
 
  private:
   friend class base::RefCountedThreadSafe<UserScriptListener>;
 
   typedef std::list<URLPattern> URLPatterns;
 
-  ~UserScriptListener();
+  virtual ~UserScriptListener();
 
   // Resume any requests that we delayed in order to wait for user scripts.
   void StartDelayedRequests();
 
   // Appends new url patterns to our list, also setting user_scripts_ready_
   // to false.
   void AppendNewURLPatterns(const URLPatterns& new_patterns);
 
   // Replaces our url pattern list. This is only used when patterns have been
   // deleted, so user_scripts_ready_ remains unchanged.
@@ skipping 29 matching lines @@
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
                        const NotificationDetails& details);
 
   NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(UserScriptListener);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_USER_SCRIPT_LISTENER_H_