1) Add initialization error page; 2) Add connection error page.

chrome/browser/resources/chromeos/login/host-pairing-screen.html

 <!-- Copyright 2015 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. -->
 
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/classes/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-iconset-svg/iron-iconset-svg.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/animations/fade-in-animation.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/animations/fade-out-animation.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/neon-animatable-behavior.html">
@@ skipping 31 matching lines @@
   <link rel="stylesheet" href="oobe_screen_host_pairing.css">
 
   <template>
     <neon-animated-pages attr-for-selected="name" selected="[[C.page]]"
         entry-animation="fade-in-animation" exit-animation="fade-out-animation">
       <host-pairing-page name="welcome">
         <div class="title" i18n-content="loginHostPairingScreenWelcomeTitle">
         </div>
         <div i18n-content="loginHostPairingScreenWelcomeText"></div>
       </host-pairing-page>
+      <host-pairing-page name="initialization-error">
+        <div class="title"
+            i18n-content="loginHostPairingScreenInitializationErrorTitle">
+        </div>
+        <div i18n-content="loginHostPairingScreenErrorNeedRestartText"></div>
+      </host-pairing-page>
       <host-pairing-page name="code-confirmation">
         <div class="title"
             i18n-content="loginHostPairingScreenConfirmationTitle">
         </div>
         <div id="code">{{C.code}}</div>
       </host-pairing-page>
+      <host-pairing-page name="connection-error">
+        <div class="title"
+            i18n-content="loginHostPairingScreenConnectionErrorTitle">
+        </div>
+        <div i18n-content="loginHostPairingScreenErrorNeedRestartText"></div>
+      </host-pairing-page>
       <host-pairing-page name="setup-basic-configuration">
         <div class="title"
             i18n-content="loginHostPairingScreenSetupBasicConfigTitle">
         </div>
       </host-pairing-page>
       <host-pairing-page name="setup-network-error">
         <div class="title"
             i18n-content="loginHostPairingScreenSetupNetworkErrorTitle">
         </div>
+        <div i18n-content="loginHostPairingScreenErrorNeedRestartText"></div>
       </host-pairing-page>
       <host-pairing-page name="update">
         <div class="title" i18n-content="loginHostPairingScreenUpdatingTitle">
         </div>
       </host-pairing-page>
       <host-pairing-page name="enrollment-introduction">
         <div class="title" i18n-content="loginHostPairingScreenEnrollTitle">
         </div>
       </host-pairing-page>
       <host-pairing-page name="enrollment">
         <div class="title">
           <!-- 'enrollmentTitle' contains <strong> tag. We need to wrap it in
                'html-echo' to prevent HTML escaping. -->
           <html-echo content="[[getEnrollmentStepTitle_(C.enrollmentDomain)]]">
           </html-echo>
         </div>
       </host-pairing-page>
       <host-pairing-page name="enrollment-error">
         <div class="title"
             i18n-content="loginHostPairingScreenEnrollmentErrorTitle">
         </div>
-        <div i18n-content="loginHostPairingScreenErrorNeedsRestart"></div>
+        <div i18n-content="loginHostPairingScreenErrorNeedRestartText"></div>
       </host-pairing-page>
       <host-pairing-page name="pairing-done">
         <div class="title" i18n-content="loginHostPairingScreenDoneTitle">
         </div>
         <div i18n-content="loginHostPairingScreenDoneText"></div>
       </host-pairing-page>
     </neon-animated-pages>
     <paper-icon-item id="device-indicator">
       <iron-icon icon="host-pairing-icons:cast" item-icon></iron-icon>
       <div id="device-label">{{C.deviceName}}</div>
     </paper-icon-item>
     <div id="illustration"></div>
   </template>
 </dom-module>