Options: lazily load Polymer when quick unlock dialog is triggered

chrome/browser/resources/options/chromeos/quick_unlock_configure_overlay.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.
 
 cr.define('options', function() {
   var Page = cr.ui.pageManager.Page;
   var PageManager = cr.ui.pageManager.PageManager;
 
   /**
    * QuickUnlockConfigureOverlay class
@@ skipping 21 matching lines @@
       };
     },
 
     /** @override */
     didClosePage: function() {
       settings.navigateTo(settings.Route.PEOPLE);
     },
 
     /** @override */
     didShowPage: function() {
+      this.ensurePolymerIsLoaded_().then(this.onPolymerLoaded_.bind(this));
+    },
+
+    /**
+     * @return {!Promise}
+     * @private
+     */
+    ensurePolymerIsLoaded_: function() {
+      this.loaded_ = this.loaded_ || new Promise(function(resolve) {
+        var link = document.createElement('link');
+        link.rel = 'import';
+        link.href = 'chrome://settings-frame/options_polymer.html';
+        link.onload = resolve;
+        document.head.appendChild(link);
+      });
+      return this.loaded_;
+    },
+
+    /**
+     * Called when polymer has been loaded and the dialog should be displayed.
+     * @private
+     */
+    onPolymerLoaded_: function() {
       settings.navigateTo(settings.Route.LOCK_SCREEN);
       var lockScreen = document.querySelector('settings-lock-screen');
 
       var checkbox =
           lockScreen.root.querySelector('div.settings-box.single-column');
       checkbox.hidden = true;
 
       var passwordPrompt = lockScreen.root.
           querySelector('settings-password-prompt-dialog');
       passwordPrompt.addEventListener('close', function() {
         if (!lockScreen.setModes_) {
           QuickUnlockConfigureOverlay.dismiss();
         }
       }.bind(this));
     },
-
   };
 
   QuickUnlockConfigureOverlay.dismiss = function() {
     PageManager.closeOverlay();
   };
 
   // Export
   return {
     QuickUnlockConfigureOverlay: QuickUnlockConfigureOverlay
   };
 });