Virtual destructors should have virtual keyword.

chrome/browser/net/net_pref_observer.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_NET_NET_PREF_OBSERVER_H_
 #define CHROME_BROWSER_NET_NET_PREF_OBSERVER_H_
 #pragma once
 
 #include <string>
 
@@ skipping 10 matching lines @@
 // Monitors network-related preferences for changes and applies them.
 // The supplied PrefService must outlive this NetPrefObserver.
 // Must be used only on the UI thread.
 class NetPrefObserver : public NotificationObserver {
  public:
   // |prefs| must be non-NULL and |*prefs| must outlive this.
   // |prerender_manager| may be NULL. If not, |*prerender_manager| must
   // outlive this.
   NetPrefObserver(PrefService* prefs,
                   prerender::PrerenderManager* prerender_manager);
-  ~NetPrefObserver();
+  virtual ~NetPrefObserver();
 
   // NotificationObserver
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
                        const NotificationDetails& details);
 
   static void RegisterPrefs(PrefService* prefs);
 
  private:
   // If |pref_name| is NULL, all monitored preferences will be applied.
   void ApplySettings(const std::string* pref_name);
 
   BooleanPrefMember network_prediction_enabled_;
   BooleanPrefMember spdy_disabled_;
   BooleanPrefMember http_throttling_enabled_;
   prerender::PrerenderManager* prerender_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(NetPrefObserver);
 };
 
 #endif  // CHROME_BROWSER_NET_NET_PREF_OBSERVER_H_
-