Virtual destructors should have virtual keyword.

chrome/test/test_notification_tracker.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_TEST_TEST_NOTIFICATION_TRACKER_H_
 #define CHROME_TEST_TEST_NOTIFICATION_TRACKER_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 13 matching lines @@
 
     NotificationType type;
     NotificationSource source;
     NotificationDetails details;
   };
 
   // By default, it won't listen for any notifications. You'll need to call
   // ListenFor for the notifications you are interested in.
   TestNotificationTracker();
 
-  ~TestNotificationTracker();
+  virtual ~TestNotificationTracker();
 
   // Makes this object listen for the given notification with the given source.
   void ListenFor(NotificationType type, const NotificationSource& source);
 
   // Makes this object listen for notifications of the given type coming from
   // any source.
   void ListenForAll(NotificationType type);
 
   // Clears the list of events.
   void Reset();
@@ skipping 28 matching lines @@
  private:
   NotificationRegistrar registrar_;
 
   // Lists all received since last cleared, in the order they were received.
   std::vector<Event> events_;
 
   DISALLOW_COPY_AND_ASSIGN(TestNotificationTracker);
 };
 
 #endif  // CHROME_TEST_TEST_NOTIFICATION_TRACKER_H_