The webkit java applet creation code passes in the baseURL which is typically...

webkit/glue/webframeloaderclient_impl.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.
 
 #ifndef WEBKIT_GLUE_WEBFRAMELOADERCLIENT_IMPL_H__
 #define WEBKIT_GLUE_WEBFRAMELOADERCLIENT_IMPL_H__
 
 #include "base/compiler_specific.h"
 
 MSVC_PUSH_WARNING_LEVEL(0);
@@ skipping 167 matching lines @@
                                         const WebCore::KURL&,
                                         const WTF::Vector<WebCore::String>&,
                                         const WTF::Vector<WebCore::String>&,
                                         const WebCore::String&,
                                         bool loadManually);
   virtual void redirectDataToPlugin(WebCore::Widget* pluginWidget);
 
   virtual WebCore::Widget* createJavaAppletWidget(
       const WebCore::IntSize&,
       WebCore::HTMLAppletElement*,
-      const WebCore::KURL& baseURL,
+      const WebCore::KURL& /* base_url */,
       const WTF::Vector<WebCore::String>& paramNames,
       const WTF::Vector<WebCore::String>& paramValues);
 
   virtual WebCore::ObjectContentType objectContentType(const WebCore::KURL& url,
                                               const WebCore::String& mimeType);
   virtual WebCore::String overrideMediaType() const;
 
   virtual void didPerformFirstNavigation() const;
 
   virtual void registerForIconNotification(bool listen = true);
@@ skipping 51 matching lines @@
   WebPluginContainer* plugin_widget_;
   // Indicates if we need to send over the initial notification to the plugin
   // which specifies that the plugin should be ready to accept data.
   bool sent_initial_response_to_plugin_;
 
   // The disposition to use for the next call to dispatchCreatePage.
   WindowOpenDisposition next_window_open_disposition_;
 };
 
 #endif  // #ifndef WEBKIT_GLUE_WEBFRAMELOADERCLIENT_IMPL_H__