[MD settings] remove unneeded properties

chrome/browser/resources/settings/settings_menu/settings_menu.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-menu' shows a menu with a hardcoded set of pages and subpages.
  *
  * Example:
  *
  *     <settings-menu selected-page-id="{{selectedPageId}}">
  *     </settings-menu>
  */
 Polymer({
   is: 'settings-menu',
 
   properties: {
-    /** @private */
-    advancedOpened_: Boolean,
-
-    /** @private */
-    basicOpened_: Boolean,
-
     /**
      * The current active route.
      */
     currentRoute: {
       type: Object,
       notify: true,
       observer: 'currentRouteChanged_',
     },
   },
 
   /** @private */
   currentRouteChanged_: function() {
-    var submenu = this.shadowRoot.querySelector(
-        'paper-submenu[data-page="' + this.currentRoute.page + '"]');
-    if (submenu)
-      submenu.opened = true;
+    // Sync URL changes to the side nav menu.
+
+    this.$.advancedPage.opened = this.currentRoute.page == 'advanced';

[dpapad, 2016/05/03 01:00:02]

Did you consider updating those 4 properties via bindings instead?

No need to change, I am just curious because I have faced the same dilemma in
the past (update N properties in a centralized spot  programatically VS spread N
data bindings in HTML).

[dschuyler, 2016/05/03 20:48:53]

Yeah, it's nicer if these are in bound in the html, imo.
The reason for them being here is for URL changes. I.e.
navigating directly to a url such as chrome://md-settings/reset

+    this.$.basicPage.opened = this.currentRoute.page == 'basic';
+
+    if (this.$.advancedPage.opened)
+      this.$.advancedMenu.selected = this.currentRoute.section;
+
+    if (this.$.basicPage.opened)
+      this.$.basicMenu.selected = this.currentRoute.section;
   },
 
   /** @private */
   openPage_: function(event) {
-    var submenuRoute = event.currentTarget.dataset.page;
+    var submenuRoute = event.currentTarget.parentNode.dataset.page;
     if (submenuRoute) {
       this.currentRoute = {
         page: submenuRoute,
         section: event.currentTarget.dataset.section,
         subpage: [],
       };
     }
   },
 
   /**
    * @param {boolean} opened Whether the menu is expanded.
    * @return {string} Which icon to use.
    * @private
    * */
   arrowState_: function(opened) {
     return opened ? 'arrow-drop-up' : 'arrow-drop-down';
   },
 });