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

chrome/common/net/gaia/gaia_auth_fetcher_unittest.cc

 // 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.
 //
 // A complete set of unit tests for GaiaAuthFetcher.
 // Originally ported from GoogleAuthenticator tests.
 
 #include <string>
 
 #include "base/json/json_reader.h"
@@ skipping 395 matching lines @@
 TEST_F(GaiaAuthFetcherTest, CaptchaParse) {
   net::URLRequestStatus status(net::URLRequestStatus::SUCCESS, 0);
   std::string data = "Url=http://www.google.com/login/captcha\n"
                      "Error=CaptchaRequired\n"
                      "CaptchaToken=CCTOKEN\n"
                      "CaptchaUrl=Captcha?ctoken=CCTOKEN\n";
   GoogleServiceAuthError error =
       GaiaAuthFetcher::GenerateAuthError(data, status);
 
   std::string token = "CCTOKEN";
-  GURL image_url("http://www.google.com/accounts/Captcha?ctoken=CCTOKEN");
+  GURL image_url("http://accounts.google.com/Captcha?ctoken=CCTOKEN");
   GURL unlock_url("http://www.google.com/login/captcha");
 
   EXPECT_EQ(error.state(), GoogleServiceAuthError::CAPTCHA_REQUIRED);
   EXPECT_EQ(error.captcha().token, token);
   EXPECT_EQ(error.captcha().image_url, image_url);
   EXPECT_EQ(error.captcha().unlock_url, unlock_url);
 }
 
 TEST_F(GaiaAuthFetcherTest, AccountDeletedError) {
   net::URLRequestStatus status(net::URLRequestStatus::SUCCESS, 0);
@@ skipping 598 matching lines @@
       .Times(1);
 
   GaiaAuthFetcher auth(&consumer, std::string(),
       profile_.GetRequestContext());
   net::URLRequestStatus status(net::URLRequestStatus::SUCCESS, 0);
   MockFetcher mock_fetcher(
       oauth_login_gurl_, status, net::HTTP_OK, cookies_, data,
       content::URLFetcher::GET, &auth);
   auth.OnURLFetchComplete(&mock_fetcher);
 }