Add Active Directory login UI tests

chromeos/dbus/fake_auth_policy_client.cc

Index: chromeos/dbus/fake_auth_policy_client.cc
diff --git a/chromeos/dbus/fake_auth_policy_client.cc b/chromeos/dbus/fake_auth_policy_client.cc
index 819105fb7921ee0ddfc1c363945d0a55bb02a8a4..0231e29fb2f6ccd1d6e9b67db672ce2d6b676710 100644
--- a/chromeos/dbus/fake_auth_policy_client.cc
+++ b/chromeos/dbus/fake_auth_policy_client.cc
@@ -113,8 +113,9 @@ void FakeAuthPolicyClient::AuthenticateUser(
     callback.Run(authpolicy::ERROR_DBUS_FAILURE, account_data);
     return;
   }
-  account_data.set_account_id(base::MD5String(user_principal_name));
-  callback.Run(authpolicy::ERROR_NONE, account_data);
+  if (auth_error_ == authpolicy::ERROR_NONE)
+    account_data.set_account_id(base::MD5String(user_principal_name));
+  callback.Run(auth_error_, account_data);
 }
 
 void FakeAuthPolicyClient::RefreshDevicePolicy(