Add the "virtual" keyword on method overrides that are missing it.

chrome/plugin/npobject_stub.h

 // Copyright (c) 2006-2008 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 class that receives IPC messages from an NPObjectProxy and calls the real
 // NPObject.
 
 #ifndef CHROME_PLUGIN_NPOBJECT_STUB_H_
 #define CHROME_PLUGIN_NPOBJECT_STUB_H_
 #pragma once
@@ skipping 21 matching lines @@
                      public NPObjectBase {
  public:
   NPObjectStub(NPObject* npobject,
                PluginChannelBase* channel,
                int route_id,
                gfx::NativeViewId containing_window,
                const GURL& page_url);
   ~NPObjectStub();
 
   // IPC::Message::Sender implementation:
-  bool Send(IPC::Message* msg);
+  virtual bool Send(IPC::Message* msg);
 
   // Called when the plugin widget that this NPObject came from is destroyed.
   // This is needed because the renderer calls NPN_DeallocateObject on the
   // window script object on destruction to avoid leaks.
   void OnPluginDestroyed();
 
   // NPObjectBase implementation.
-  virtual NPObject* GetUnderlyingNPObject() {
-    return npobject_;
-  }
+  virtual NPObject* GetUnderlyingNPObject();
 
-  IPC::Channel::Listener* GetChannelListener() {
-    return static_cast<IPC::Channel::Listener*>(this);
-  }
+  virtual IPC::Channel::Listener* GetChannelListener();
 
  private:
   // IPC::Channel::Listener implementation:
-  void OnMessageReceived(const IPC::Message& message);
-  void OnChannelError();
+  virtual void OnMessageReceived(const IPC::Message& message);
+  virtual void OnChannelError();
 
   // message handlers
   void OnRelease(IPC::Message* reply_msg);
   void OnHasMethod(const NPIdentifier_Param& name,
                    bool* result);
   void OnInvoke(bool is_default,
                 const NPIdentifier_Param& method,
                 const std::vector<NPVariant_Param>& args,
                 IPC::Message* reply_msg);
   void OnHasProperty(const NPIdentifier_Param& name,
@@ skipping 18 matching lines @@
   NPObject* npobject_;
   scoped_refptr<PluginChannelBase> channel_;
   int route_id_;
   gfx::NativeViewId containing_window_;
 
   // The url of the main frame hosting the plugin.
   GURL page_url_;
 };
 
 #endif  // CHROME_PLUGIN_NPOBJECT_STUB_H_