Create implementation of the side panel using a dialog.

chrome/browser/resources/settings/settings_ui/settings_ui.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-ui' implements the UI for the Settings page.
  *
  * Example:
  *
@@ skipping 54 matching lines @@
     settings.initializeRouteFromUrl();
   },
 
   /**
    * @override
    * @suppress {es5Strict} Object literals cannot contain duplicate keys in ES5
    *     strict mode.
    */
   ready: function() {
     // Lazy-create the drawer the first time it is opened or swiped into view.
-    var drawer = assert(this.$$('app-drawer'));
-    listenOnce(drawer, 'track opened-changed', function() {
+    listenOnce(this.$.drawer, 'track opened-changed', function() {
       this.$.drawerTemplate.if = true;
     }.bind(this));
 
     window.addEventListener('popstate', function(e) {
-      drawer.close();
+      this.$.drawer.close();
     }.bind(this));
 
     if (loadTimeData.getBoolean('isGuest')) {
       this.pageVisibility_ = {
         people: false,
         onStartup: false,
         reset: false,
 <if expr="not chromeos">
         appearance: false,
         defaultBrowser: false,
@@ skipping 75 matching lines @@
         query.length > 0 ?
             new URLSearchParams(`search=${query}`) : undefined);
   },
 
   /**
    * @param {Event} event
    * @private
    */
   onIronActivate_: function(event) {
     if (event.detail.item.id != 'advancedPage')
-      this.$$('app-drawer').close();
+      this.$.drawer.close();
   },
 
   /** @private */
   onMenuButtonTap_: function() {
-    this.$$('app-drawer').toggle();
+    this.$.drawer.toggle();
   },
 
   /** @private */
   directionDelegateChanged_: function() {
-    this.$$('app-drawer').align = this.directionDelegate.isRtl() ?
+    this.$.drawer.align = this.directionDelegate.isRtl() ?
         'right' : 'left';
   },
 });