Virtual destructors should have virtual keyword.

chrome/browser/extensions/extension_toolbar_model.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_EXTENSION_TOOLBAR_MODEL_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_TOOLBAR_MODEL_H_
 #pragma once
 
 #include "base/observer_list.h"
 #include "chrome/common/extensions/extension.h"
 #include "content/common/notification_observer.h"
 #include "content/common/notification_registrar.h"
 
 class ExtensionService;
 class PrefService;
 
 // Model for the browser actions toolbar.
 class ExtensionToolbarModel : public NotificationObserver {
  public:
   explicit ExtensionToolbarModel(ExtensionService* service);
-  ~ExtensionToolbarModel();
+  virtual ~ExtensionToolbarModel();
 
   // A class which is informed of changes to the model; represents the view of
   // MVC.
   class Observer {
    public:
     // An extension with a browser action button has been added, and should go
     // in the toolbar at |index|.
     virtual void BrowserActionAdded(const Extension* extension, int index) {}
 
     // The browser action button for |extension| should no longer show.
@@ skipping 78 matching lines @@
   size_t last_extension_removed_index_;
 
   // The number of icons visible (the rest should be hidden in the overflow
   // chevron).
   int visible_icon_count_;
 
   NotificationRegistrar registrar_;
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_TOOLBAR_MODEL_H_