GCMS has automatic checks for CheckExternalConnections. It will be

chrome/browser/signin/account_reconcilor_unittest.cc

 // Copyright 2013 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.
 
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/run_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/histogram_tester.h"
 #include "base/time/time.h"
@@ skipping 131 matching lines @@
     base::CommandLine::ForCurrentProcess()->AppendSwitch(
         switches::kEnableNewProfileManagement);
   }
 
   list_accounts_url_ = GaiaUrls::GetInstance()->ListAccountsURLWithSource(
       GaiaConstants::kReconcilorSource);
   get_check_connection_info_url_ =
       GaiaUrls::GetInstance()->GetCheckConnectionInfoURLWithSource(
           GaiaConstants::kChromeSource);
 
-  SetFakeResponse(get_check_connection_info_url().spec(), "[]",
-      net::HTTP_OK, net::URLRequestStatus::SUCCESS);
+  // Specific tests may set a response that includes specific accounts.
+  SetFakeResponse(list_accounts_url().spec(), "",
+      net::HTTP_NOT_FOUND, net::URLRequestStatus::SUCCESS);
 
   testing_profile_manager_.reset(
       new TestingProfileManager(TestingBrowserProcess::GetGlobal()));
   ASSERT_TRUE(testing_profile_manager_.get()->SetUp());
 
   TestingProfile::TestingFactories factories;
   factories.push_back(std::make_pair(ChromeSigninClientFactory::GetInstance(),
       signin::BuildTestSigninClient));
   factories.push_back(std::make_pair(
       ProfileOAuth2TokenServiceFactory::GetInstance(),
@@ skipping 548 matching lines @@
   ASSERT_TRUE(reconcilor->is_reconcile_started_);
 
   SimulateAddAccountToCookieCompleted(reconcilor, "user@gmail.com",
                                       GoogleServiceAuthError::AuthErrorNone());
   ASSERT_FALSE(reconcilor->is_reconcile_started_);
 }
 
 INSTANTIATE_TEST_CASE_P(AccountReconcilorMaybeEnabled,
                         AccountReconcilorTest,
                         testing::Bool());