[MD settings] idle load basic and advanced pages

chrome/browser/resources/settings/basic_page/basic_page.js

 // Copyright 2015 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
  * 'settings-basic-page' is the settings page containing the actual settings.
  */
 Polymer({
   is: 'settings-basic-page',
@@ skipping 11 matching lines @@
 
     /**
      * Dictionary defining page visibility.
      * @type {!GuestModePageVisibility}
      */
     pageVisibility: Object,
 
     advancedToggleExpanded: {
       type: Boolean,
       notify: true,
+      observer: 'advancedToggleExpandedChanged_',
     },
 
     /**
      * True if a section is fully expanded to hide other sections beneath it.
      * False otherwise (even while animating a section open/closed).
      * @private {boolean}
      */
     hasExpandedSection_: {
       type: Boolean,
       value: false,
@@ skipping 52 matching lines @@
    * @param {string} query The text to search for.
    * @return {!Promise<!settings.SearchRequest>} A signal indicating that
    *     searching finished.
    */
   searchContents: function(query) {
     var whenSearchDone = settings.getSearchManager().search(
         query, assert(this.$$('#basicPage')));
 
     if (this.pageVisibility.advancedSettings !== false) {
       assert(whenSearchDone === settings.getSearchManager().search(
-          query, assert(this.$$('#advancedPage'))));
+          query, assert(this.$.advancedPageTemplate.get())));
     }
 
     return whenSearchDone;
   },
 
   /** @private */
   onResetDone_: function() {
     this.showResetProfileBanner_ = false;
   },
 
   /**
    * @return {boolean}
    * @private
    */
   shouldShowAndroidApps_: function() {
     var visibility = /** @type {boolean|undefined} */ (
         this.get('pageVisibility.androidApps'));
     return this.showAndroidApps && this.showPage(visibility);
   },
 
   /**
    * Hides everything but the newly expanded subpage.
    * @private
    */
   onSubpageExpanded_: function() {
     this.hasExpandedSection_ = true;
   },
 
   /**
+   * Inform the idle render code that the advanced page to load.

[dpapad, 2017/01/31 23:10:13]

Syntax is confusing, probably something is missing from this sentence.

[dschuyler, 2017/01/31 23:53:03]

Done.

+   * @private
+   */
+  advancedToggleExpandedChanged_: function() {
+    if (this.advancedToggleExpanded)
+      this.$.advancedPageTemplate.get();
+  },
+
+  /**
    * @param {boolean} inSearchMode
    * @param {boolean} hasExpandedSection
    * @return {boolean}
    * @private
    */
   showAdvancedToggle_: function(inSearchMode, hasExpandedSection) {
     return !inSearchMode && !hasExpandedSection;
   },
 
   /**
@@ skipping 35 matching lines @@
 
   /**
    * @param {boolean} opened Whether the menu is expanded.
    * @return {string} Icon name.
    * @private
    */
   getArrowIcon_: function(opened) {
     return opened ? 'cr:arrow-drop-up' : 'cr:arrow-drop-down';
   },
 });