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

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

Index: chrome/browser/resources/chromeos/login/screen_offline_message.js
diff --git a/chrome/browser/resources/chromeos/login/screen_offline_message.js b/chrome/browser/resources/chromeos/login/screen_offline_message.js
index 7bb6c7d063ee841cada2a7f3ae4614b092e26df2..1d52a989c8859e3b8b05d8756cd16f20b2b3f16e 100644
--- a/chrome/browser/resources/chromeos/login/screen_offline_message.js
+++ b/chrome/browser/resources/chromeos/login/screen_offline_message.js
@@ -33,10 +33,9 @@ cr.define('login', function() {
 
     /** @inheritDoc */
     decorate: function() {
-      window.addEventListener('online',
-                              this.handleNetworkStateChange_.bind(this));
-      window.addEventListener('offline',
-                              this.handleNetworkStateChange_.bind(this));
+      chrome.send('loginAddNetworkStateObserver',
+                  ['login.OfflineMessageScreen.updateState']);
+
       cr.ui.DropDown.decorate($('offline-networks-list'));
     },
 
@@ -48,20 +47,26 @@ cr.define('login', function() {
       cr.ui.DropDown.setActive('offline-networks-list', false);
     },
 
+    update: function() {
+      chrome.send('loginRequestNetworkState',
+                  ['login.OfflineMessageScreen.updateState']);
+    },
+
     /**
      * Shows or hides offline message based on network on/offline state.
      */
-    update: function() {
+    updateState: function(state) {
       var currentScreen = Oobe.getInstance().currentScreen;
       var offlineMessage = this;
-      var isOffline = !window.navigator.onLine;
+      var isOnline = state == 1;
+      var isUnderCaptivePortal = state == 2;
       var shouldOverlay = MANAGED_SCREENS.indexOf(currentScreen.id) != -1;
 
-      if (isOffline && shouldOverlay) {
+      if (!isOnline && shouldOverlay) {
         offlineMessage.onBeforeShow();
 
-        $('offline-message-text').hidden = false;
-        $('captive-portal-message-text').hidden = true;
+        $('offline-message-text').hidden = isUnderCaptivePortal;
+        $('captive-portal-message-text').hidden = !isUnderCaptivePortal;
 
         offlineMessage.classList.remove('hidden');
         offlineMessage.classList.remove('faded');
@@ -92,13 +97,15 @@ cr.define('login', function() {
         }
       }
     },
+  };
 
-    /**
-     * Handler of online/offline event.
-     */
-    handleNetworkStateChange_: function() {
-      this.update();
-    }
+  /**
+   * Network state changed callback.
+   * @param {Integer} state Current state of the network: 0 - offline;
+   * 1 - online; 2 - under the captive portal.
+   */
+  OfflineMessageScreen.updateState = function(state) {
+    $('offline-message').updateState(state);
   };
 
   /**