[cros,login] Pre-load login extension in the background.

chrome/browser/resources/chromeos/login/screen_gaia_signin.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 Oobe signin screen implementation.
  */
 
 cr.define('login', function() {
 
@@ skipping 80 matching lines @@
 
       this.showLoadingUI_(loading);
     },
 
     /**
      * Event handler that is invoked just before the frame is shown.
      * @param data {string} Screen init payload. Url of auth extension start
      *        page.
      */
     onBeforeShow: function(data) {
-      console.log('Opening extension: ' + data.startUrl +
-                  ', opt_email=' + data.email);
+      // Announce the name of the screen, if accessibility is on.
+      $('gaia-signin-aria-label').setAttribute(
+          'aria-label', localStrings.getString('signinScreenTitle'));
+
+      // Button header is always visible when sign in is presented.
+      // Header is hidden once GAIA reports on successful sign in.
+      Oobe.getInstance().headerHidden = false;
+    },
+
+    setExtensionUrl_: function(data) {
+      $('createAccount').hidden = !data.createAccount;
+      $('guestSignin').hidden = !data.guestSignin;
 
       var params = [];
       if (data.gaiaOrigin)
         params.push('gaiaOrigin=' + encodeURIComponent(data.gaiaOrigin));
       if (data.hl)
         params.push('hl=' + encodeURIComponent(data.hl));
       if (data.email)
         params.push('email=' + encodeURIComponent(data.email));
       if (data.test_email)
         params.push('test_email=' + encodeURIComponent(data.test_email));
       if (data.test_password)
         params.push('test_password=' + encodeURIComponent(data.test_password));
 
       var url = data.startUrl;
       if (params.length)
         url += '?' + params.join('&');
 
-      $('signin-frame').src = url;
-      this.extension_url_ = url;
+      if (data.forceReload || this.extension_url_ != url) {
+        console.log('Opening extension: ' + data.startUrl +
+                    ', opt_email=' + data.email);
 
-      $('createAccount').hidden = !data.createAccount;
-      $('guestSignin').hidden = !data.guestSignin;
+        $('signin-frame').src = url;
+        this.extension_url_ = url;
 
-      // Announce the name of the screen, if accessibility is on.
-      $('gaia-signin-aria-label').setAttribute(
-          'aria-label', localStrings.getString('signinScreenTitle'));
-
-      // Button header is always visible when sign in is presented.
-      // Header is hidden once GAIA reports on successful sign in.
-      Oobe.getInstance().headerHidden = false;
-
-      this.loading = true;
-      this.clearRetry_();
+        this.loading = true;
+        this.clearRetry_();
+      } else if (this.loading) {
+        // Probably an error has occurred, so trying to reload.
+        this.doReload();
+      }
     },
 
     /**
      * Checks if message comes from the loaded authentication extension.
      * @param e {object} Payload of the received HTML5 message.
      * @type {bool}
      */
     isAuthExtMessage_: function(e) {
       return this.extension_url_ != null &&
           this.extension_url_.indexOf(e.origin) == 0 &&
@@ skipping 62 matching lines @@
 
       var delay = Math.pow(2, this.retryCount_) * 5;
       delay = Math.max(MIN_DELAY, Math.min(MAX_DELAY, delay)) * 1000;
 
       ++this.retryCount_;
       this.retryTimer_ = window.setTimeout(this.doReload.bind(this), delay);
       console.log('GaiaSigninScreen scheduleRetry in ' + delay + 'ms.');
     }
   };
 
+  GaiaSigninScreen.setExtensionUrl = function(data) {
+    $('gaia-signin').setExtensionUrl_(data);
+  };
+
   return {
     GaiaSigninScreen: GaiaSigninScreen
   };
 });