[cros,webui] Captive portal on login screen proper handling.

chrome/browser/resources/chromeos/login/header_bar.js

Index: chrome/browser/resources/chromeos/login/header_bar.js
diff --git a/chrome/browser/resources/chromeos/login/header_bar.js b/chrome/browser/resources/chromeos/login/header_bar.js
index 7bf6038fa86727e0c030530cea187648a0a66542..2da030242ed479ca1065acfe7c414e04fd787c1c 100644
--- a/chrome/browser/resources/chromeos/login/header_bar.js
+++ b/chrome/browser/resources/chromeos/login/header_bar.js
@@ -25,12 +25,8 @@ cr.define('login', function() {
       $('shutdown-button').addEventListener('click',
           this.handleShutdownClick_);
       $('add-user-button').addEventListener('click', function(e) {
-        if (window.navigator.onLine) {
-          Oobe.showSigninUI();
-        } else {
-          $('bubble').showTextForElement($('add-user-button'),
-              localStrings.getString('addUserOfflineMessage'));
-        }
+        chrome.send('loginRequestNetworkState',
+                    ['login.HeaderBar.updateState']);
       });
       $('cancel-add-user-button').addEventListener('click', function(e) {
         this.hidden = true;
@@ -48,6 +44,21 @@ cr.define('login', function() {
     }
   };
 
+  /**
+   * Network state changed callback.
+   * @param {Integer} state Current state of the network: 0 - offline;
+   * 1 - online; 2 - under the captive portal.
+   */
+  HeaderBar.updateState = function(state) {
+    var isOffline = state == 0;
+    if (!isOffline) {
+      Oobe.showSigninUI();
+    } else {
+      $('bubble').showTextForElement($('add-user-button'),
+          localStrings.getString('addUserOfflineMessage'));
+    }
+  }
+
   return {
     HeaderBar: HeaderBar
   };