GCMS has automatic checks for CheckExternalConnections. It will be

chrome/browser/signin/account_reconcilor_unittest.cc

Index: chrome/browser/signin/account_reconcilor_unittest.cc
diff --git a/chrome/browser/signin/account_reconcilor_unittest.cc b/chrome/browser/signin/account_reconcilor_unittest.cc
index 5bf5c539c8801aefe873854eeb81bb6a7dc62773..43f97c4d7d348a7b3f0f698bbafce6fa8c13519f 100644
--- a/chrome/browser/signin/account_reconcilor_unittest.cc
+++ b/chrome/browser/signin/account_reconcilor_unittest.cc
@@ -149,8 +149,9 @@ void AccountReconcilorTest::SetUp() {
       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()));