[MD settings] side nav routing to page sections

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:
  *
@@ skipping 27 matching lines @@
     if (submenu)
       submenu.opened = true;
   },
 
   /** @private */
   openPage_: function(event) {
     var submenuRoute = event.currentTarget.dataset.page;
     if (submenuRoute) {
       this.currentRoute = {
         page: submenuRoute,
-        section: '',
+        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';
   },
 });