It seems GAIA had changed dosserver rules today, so we can go back to accounts.google.com.

chrome/common/net/url_util.h

 // Copyright (c) 2012 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 CHROME_COMMON_NET_URL_UTIL_H_
 #define CHROME_COMMON_NET_URL_UTIL_H_
 #pragma once
 
 #include <string>
 
@@ skipping 34 matching lines @@
 // AppendOrReplaceQueryParameter(
 //     GURL("http://example.com"), "name", "new").spec()
 // => "http://example.com?name=value"
 // AppendOrReplaceQueryParameter(
 //     GURL("http://example.com?x=y&name=old"), "name", "new").spec()
 // => "http://example.com?x=y&name=new"
 GURL AppendOrReplaceQueryParameter(const GURL& url,
                                    const std::string& name,
                                    const std::string& value);
 
+// Looks for |search_key| in the query portion of |url|. Returns true if the
+// key is found and sets |out_value| to the unescaped value for the key.
+// Returns false if the key is not found.
+bool GetValueForKeyInQuery(const GURL& url,
+                           const std::string& search_key,
+                           std::string* out_value);
+
 }  // namespace chrome_common_net
 
 #endif  // CHROME_COMMON_NET_URL_UTIL_H_