Update readyForTesting var even on Oobe.initialize() failure.

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

 // Copyright 2016 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 Common OOBE controller methods. This method is shared between
  * OOBE, login, and the lock screen. Add only methods that need to be shared
  * between all *three* screens here, as each additional method increases the
  * time it takes to show the lock screen.
  *
@@ skipping 264 matching lines @@
   /**
    * Restores input focus to currently selected pod.
    */
   Oobe.refocusCurrentPod = function() {
     DisplayManager.refocusCurrentPod();
   };
 
   /**
    * Some ForTesting APIs directly access to DOM. Because this script is loaded
    * in header, DOM tree may not be available at beginning.
-   * In DOMContentLoaded, this is marked to true, indicating ForTesting methods
-   * can be called.
+   * This is initialized to null, indicating that DOM is not yet loaded. Then
+   * marked to "true" on success of Oobe initialization, or "false" on failure,
+   * which runs after DOM loading is done.
+   * If "true" is set, external scripts can call ForTesting APIs defined in
+   * this module.
+   * Note that "false" is explicitly set there to notify the caller that
+   * the initialization is failed, so it is not necessary to wait for timeout.
    * External script using ForTesting APIs should wait for this condition.
-   * @type {boolean}
+   * @type {?boolean}
    */
-  Oobe.readyForTesting = false;
+  Oobe.readyForTesting = null;
 
   /**
    * Skip to login screen for telemetry.
    */
   Oobe.skipToLoginForTesting = function() {
     Oobe.disableSigninUI();
     chrome.send('skipToLoginForTesting');
   };
 
   /**
@@ skipping 141 matching lines @@
   return src instanceof HTMLTextAreaElement ||
          src instanceof HTMLInputElement &&
          /text|password|search/.test(src.type);
 });
 
 
 (function() {
   'use strict';
 
   document.addEventListener('DOMContentLoaded', function() {
-    Oobe.initialize();
-    Oobe.readyForTesting = true;

[achuithb, 2017/04/17 08:42:08]

What happens if you move this line to before Oobe.initialize?

[hidehiko, 2017/04/17 09:32:27]

Acknowledged.

+    try {
+      Oobe.initialize();
+      Oobe.readyForTesting = true;
+    } catch (e) {
+      Oobe.readyForTesting = false;
+      throw e;
+    }
   });
 
   // Install a global error handler so stack traces are included in logs.
   window.onerror = function(message, file, line, column, error) {
     console.error(error.stack);
   }
 })();