Implements frame sniffer to watch iframe loading state.

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

  // Copyright (c) 2011 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.
 
 /**
  * @fileoverview Offline message screen implementation.
  */
 
 cr.define('login', function() {
   // Screens that should have offline message overlay.
@@ skipping 31 matching lines @@
     /**
      * Shows or hides offline message based on network on/offline state.
      */
     update: function() {
       var currentScreen = Oobe.getInstance().currentScreen;
       var offlineMessage = this;
       var isOffline = !window.navigator.onLine;
       var shouldOverlay = MANAGED_SCREENS.indexOf(currentScreen.id) != -1;
 
       if (isOffline && shouldOverlay) {
+        $('offline-message-text').hidden = false;
+        $('captive-portal-message-text').hidden = true;
+
         offlineMessage.classList.remove('hidden');
         offlineMessage.classList.remove('faded');
 
-        currentScreen.classList.add('faded');
-        currentScreen.addEventListener('webkitTransitionEnd',
-          function f(e) {
-            currentScreen.removeEventListener('webkitTransitionEnd', f);
-            currentScreen.classList.add('hidden');
-          });
+        if (!currentScreen.classList.contains('faded')) {
+          currentScreen.classList.add('faded');
+          currentScreen.addEventListener('webkitTransitionEnd',
+            function f(e) {
+              currentScreen.removeEventListener('webkitTransitionEnd', f);
+              currentScreen.classList.add('hidden');
+            });
+        }
       } else {
         if (!offlineMessage.classList.contains('faded')) {
           offlineMessage.classList.add('faded');
           offlineMessage.addEventListener('webkitTransitionEnd',
             function f(e) {
               offlineMessage.removeEventListener('webkitTransitionEnd', f);
               offlineMessage.classList.add('hidden');
             });
 
           currentScreen.classList.remove('hidden');
           currentScreen.classList.remove('faded');
 
           // Triggers refresh for Gaia sign-in screen.
           if (currentScreen.id == 'gaia-signin')
             chrome.send('showAddUser');
         }
       }
     },
 
     /**
      * Handler of online/offline event.
      */
     handleNetworkStateChange_: function() {
       this.update();
     }
   };
 
+  /**
+   * Handler for iframe's error notification coming from the outside.
+   * For more info see C++ class 'SnifferObserver' which calls this method.
+   * @param {integer} error Error code.
+   */
+  OfflineMessageScreen.onFrameError = function(error) {
+    var currentScreen = Oobe.getInstance().currentScreen;
+    var offlineMessage = $('offline-message');
+    var isOffline = !window.navigator.onLine;
+    var shouldOverlay = MANAGED_SCREENS.indexOf(currentScreen.id) != -1;
+
+    if (!shouldOverlay)
+      return;
+
+    if (!isOffline) {
+      $('offline-message-text').hidden = true;
+      $('captive-portal-message-text').hidden = false;
+    }
+
+    if (!currentScreen.classList.contains('faded')) {
+      offlineMessage.classList.remove('hidden');
+      offlineMessage.classList.remove('faded');
+
+      currentScreen.classList.add('faded');
+      currentScreen.addEventListener('webkitTransitionEnd',
+        function f(e) {
+          currentScreen.removeEventListener('webkitTransitionEnd', f);
+          currentScreen.classList.add('hidden');
+        });
+    }
+  };
+
   return {
     OfflineMessageScreen: OfflineMessageScreen
   };
 });