Virtual destructors should have virtual keyword.

webkit/plugins/npapi/webplugin_delegate_impl.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 WEBKIT_PLUGINS_NPAPI_WEBPLUGIN_DELEGATE_IMPL_H_
 #define WEBKIT_PLUGINS_NPAPI_WEBPLUGIN_DELEGATE_IMPL_H_
 
 #include <string>
 #include <list>
 
@@ skipping 183 matching lines @@
     windowless_shm_pixmap_ = shm_pixmap;
   }
 #endif
 
  private:
   friend class DeleteTask<WebPluginDelegateImpl>;
   friend class WebPluginDelegate;
 
   WebPluginDelegateImpl(gfx::PluginWindowHandle containing_view,
                         PluginInstance *instance);
-  ~WebPluginDelegateImpl();
+  virtual ~WebPluginDelegateImpl();
 
   // Called by Initialize() for platform-specific initialization.
   // If this returns false, the plugin shouldn't be started--see Initialize().
   bool PlatformInitialize();
 
   // Called by DestroyInstance(), used for platform-specific destruction.
   void PlatformDestroyInstance();
 
   //--------------------------
   // used for windowed plugins
@@ skipping 297 matching lines @@
   // True if NPP_New did not return an error.
   bool creation_succeeded_;
 
   DISALLOW_COPY_AND_ASSIGN(WebPluginDelegateImpl);
 };
 
 }  // namespace npapi
 }  // namespace webkit
 
 #endif  // WEBKIT_PLUGINS_NPAPI_WEBPLUGIN_DELEGATE_IMPL_H_