Virtual destructors should have virtual keyword.

content/plugin/npobject_proxy.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.
 //
 // A proxy for NPObject that sends all calls to the object to an NPObjectStub
 // running in a different process.
 
 #ifndef CONTENT_PLUGIN_NPOBJECT_PROXY_H_
 #define CONTENT_PLUGIN_NPOBJECT_PROXY_H_
 #pragma once
@@ skipping 13 matching lines @@
 // as a plugin can get an NPObject for the window, and a page can get an
 // NPObject for the plugin.  In the process that interacts with the NPobject we
 // give it an NPObjectProxy instead.  All calls to it are sent across an IPC
 // channel (specifically, a PluginChannelBase).  The NPObjectStub on the other
 // side translates the IPC messages into calls to the actual NPObject, and
 // returns the marshalled result.
 class NPObjectProxy : public IPC::Channel::Listener,
                       public IPC::Message::Sender,
                       public NPObjectBase {
  public:
-  ~NPObjectProxy();
+  virtual ~NPObjectProxy();
 
   static NPObject* Create(PluginChannelBase* channel,
                           int route_id,
                           gfx::NativeViewId containing_window,
                           const GURL& page_url);
 
   // IPC::Message::Sender implementation:
   virtual bool Send(IPC::Message* msg);
   int route_id() { return route_id_; }
   PluginChannelBase* channel() { return channel_; }
@@ skipping 69 matching lines @@
 
   scoped_refptr<PluginChannelBase> channel_;
   int route_id_;
   gfx::NativeViewId containing_window_;
 
   // The url of the main frame hosting the plugin.
   GURL page_url_;
 };
 
 #endif  // CONTENT_PLUGIN_NPOBJECT_PROXY_H_