override chrome:// URLs via extensions.

chrome/browser/browser_url_handler.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.
 
 // We handle some special browser-level URLs (like "about:version")
 // before they're handed to a renderer.  This lets us do the URL handling
 // on the browser side (which has access to more information than the
 // renderers do) as well as sidestep the risk of exposing data to
 // random web pages (because from the resource loader's perspective, these
 // URL schemes don't exist).
 
 #ifndef CHROME_BROWSER_BROWSER_URL_HANDLER_H_
 #define CHROME_BROWSER_BROWSER_URL_HANDLER_H_
 
 #include <vector>
 
 class GURL;
+class Profile;
 
 // BrowserURLHandler manages the list of all special URLs and manages
 // dispatching the URL handling to registered handlers.
 class BrowserURLHandler {
  public:
   // The type of functions that can process a URL.
   // If a handler handles |url|, it should :
   // - optionally modify |url| to the URL that should be sent to the renderer
   // - optionally set |dispatcher| to the necessary DOMMessageDispatcher
   // - return true.
   // If the URL is not handled by a handler, it should return false.
-  typedef bool (*URLHandler)(GURL* url);
+  typedef bool (*URLHandler)(GURL* url, Profile* profile);
 
   // HandleBrowserURL gives all registered URLHandlers a shot at processing
   // the given URL, and modifies it in place.
-  static void RewriteURLIfNecessary(GURL* url);
+  static void RewriteURLIfNecessary(GURL* url, Profile* profile);
 
   // We initialize the list of url_handlers_ lazily the first time MaybeHandle
   // is called.
   static void InitURLHandlers();
 
   // The list of known URLHandlers.
   static std::vector<URLHandler> url_handlers_;
 };
 
 #endif  // CHROME_BROWSER_BROWSER_URL_HANDLER_H_