Implement unregisterProtocolHandler() function on CUSTOM_SCHEME_HANDLER

public/web/WebViewClient.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 339 matching lines @@
     // Informs the browser that the zoom level has changed as a result of an
     // action that wasn't initiated by the client.
     virtual void zoomLevelChanged() { }
 
     // Registers a new URL handler for the given protocol.
     virtual void registerProtocolHandler(const WebString& scheme,
                                          const WebString& baseUrl,
                                          const WebString& url,
                                          const WebString& title) { }
 
+    // Unregisters a given URL handler for the given protocol.
+    virtual void unregisterProtocolHandler(const WebString& scheme, const WebString& baseUrl, const WebString& url) { }
+
     // Visibility -----------------------------------------------------------
 
     // Returns the current visibility of the WebView.
     virtual WebPageVisibilityState visibilityState() const
     {
         return WebPageVisibilityStateVisible;
     }
 
     // Media Streams -------------------------------------------------------
 
@@ skipping 22 matching lines @@
     // Informs the browser that the draggable regions have been updated.
     virtual void draggableRegionsChanged() { }
 
 protected:
     ~WebViewClient() { }
 };
 
 } // namespace WebKit
 
 #endif