fix quick unlock config in options

chrome/browser/resources/options/chromeos/quick_unlock_configure_overlay.js

Index: chrome/browser/resources/options/chromeos/quick_unlock_configure_overlay.js
diff --git a/chrome/browser/resources/options/chromeos/quick_unlock_configure_overlay.js b/chrome/browser/resources/options/chromeos/quick_unlock_configure_overlay.js
index b6d067801353192aad15c98251587b1b25b5594b..15efe1057b2d490e92c20fbc264c50815faabd8a 100644
--- a/chrome/browser/resources/options/chromeos/quick_unlock_configure_overlay.js
+++ b/chrome/browser/resources/options/chromeos/quick_unlock_configure_overlay.js
@@ -7,6 +7,14 @@ cr.define('options', function() {
   var PageManager = cr.ui.pageManager.PageManager;
 
   /**
+   * Maximum time to wait after the page is fully loaded before
+   * we start to load polymer elements.
+   * @type {number}
+   * @const
+   */
+  var POLYMER_LOAD_TIMEOUT_MS = 5000;
+
+  /**
    * QuickUnlockConfigureOverlay class
    * Dialog that allows users to configure screen lock.
    * @constructor
@@ -30,6 +38,16 @@ cr.define('options', function() {
       $('screen-lock-done').onclick = function() {
         QuickUnlockConfigureOverlay.dismiss();
       };
+
+      document.onreadystatechange = function () {
+        if (document.readyState == "complete") {
+          // Setting a timeout here to avoid racing with some browsertests,
+          // this should be here for only a short period of time as
+          // md-settings are lanuching soon.

[jdufault, 2017/02/15 23:53:22]

nit: are lanuching -> is launching

[xiaoyinh(OOO Sep 11-29), 2017/02/17 01:31:44]

Done.

+          setTimeout(this.ensurePolymerIsLoaded_.bind(this),
+                     POLYMER_LOAD_TIMEOUT_MS);
+        }
+      }.bind(this);
     },
 
     /** @override */
@@ -67,7 +85,7 @@ cr.define('options', function() {
 
       var checkbox =
           lockScreen.root.querySelector(
-              'div.settings-box.single-column.screen-lock');
+              'div.settings-box');
       checkbox.hidden = true;
 
       var passwordPrompt = lockScreen.root.