Refactored error screen logic.

chrome/browser/resources/chromeos/login/screen_error_message.css

 /* 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.
  */
 
 html[oobe=new] #error-message {
   min-height: 184px;
   /* Screen has no controls but has padding at the last text message */
   padding: 70px 17px 50px;
   width: 688px;
@@ skipping 14 matching lines @@
 }
 
 #captive-portal-proxy-message-text {
   margin-top: 20px;
 }
 
 #captive-portal-network-select-text {
   margin-top: 20px;
 }
 
-.show-with-offline-message,
-.show-with-captive-portal,
 .show-with-proxy-error,
+.show-with-captive-portal-error,
+.show-with-timeout-error,
+.show-with-offline-error,
 .guest-signin,
 .offline-login {
   display: none;
 }
 
-.show-offline-message .show-with-offline-message,
-.show-captive-portal .show-with-captive-portal,
+.show-captive-portal-error .show-with-captive-portal-error,
 .show-proxy-error .show-with-proxy-error,
+.show-timeout-error .show-with-timeout-error,
+.show-offline-error .show-with-offline-error,
 .allow-guest-signin .guest-signin,
 .allow-offline-login .offline-login {
   display: block;
 }
 
-.show-captive-portal .dont-show-with-captive-portal {
+.show-captive-portal-error .dont-show-with-captive-portal-error {
   display: none;
 }
 
 #error-guest-signin,
 #error-offline-login {
   -webkit-margin-start: 60px;
   margin-bottom: 21px;
 }