[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) {

[xiyuan, 2011/11/03 16:52:33]

When will the two "else" branch below get hit?

It seems a bit strange to me that a SetExtensionUrl call triggers
"loginWebuiRead".

[altimofeev, 2011/11/03 17:22:32]

* "!this.loading": first click on 'Add new user' button, after extension has
been loaded in background.
* "this.loading": first click on 'Add new user' button, loading is in progress
(probably, network error). So we try to load again.

Do you think I should change SetExtensionUrl to something which implicitly says
that this URL will also be fetched? What about 'StartExtensionLoading'?

[xiyuan, 2011/11/03 17:36:04]

In this case, if Gaia is loaded successfully, "loginWebuiRead" should be fired
already in onMessage handler and we don't need to fire it again here.
Okay. We probably need this to show proper error message.
Think a name implies loading is better. I prefer to call it "LoadExtension" or
"LoadAuthExt" etc.

[altimofeev, 2011/11/07 16:21:59]

Done - moved the logic fully to the C++ part.
Done.

+        chrome.send('loginWebuiReady');
+      } else {
+        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
   };
 });