[MD settings] close the side nav when navigating back/forward

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 48 matching lines @@
     toolbarSpinnerActive_: {
       type: Boolean,
       value: false,
     },
   },
 
   listeners: {
     'sideNav.iron-activate': 'onIronActivate_',
   },
 
+  /** @override */
+  ready: function() {
+    this.$$('cr-toolbar').addEventListener('search-changed', function(e) {
+      this.$$('settings-main').searchContents(e.detail);
+    }.bind(this));
+
+    window.addEventListener('popstate', function(e) {
+      this.$$('app-drawer').close();
+    }.bind(this));
+  },
+
   /** @private */
   onCloseAppealTap_: function() {
     window.sessionStorage.appealClosed_ = this.appealClosed_ = true;
   },
 
   /**
    * @param {Event} event
    * @private
    */
   onIronActivate_: function(event) {
     if (event.detail.item.id != 'advancedPage')
       this.$$('app-drawer').close();
   },
 
   /** @private */
   onMenuButtonTap_: function() {
     this.$$('app-drawer').toggle();
   },
 
-  /** @override */
-  ready: function() {
-    this.$$('cr-toolbar').addEventListener('search-changed', function(e) {
-      this.$$('settings-main').searchContents(e.detail);
-    }.bind(this));
-  },
-
   /** @private */
   directionDelegateChanged_: function() {
     this.$$('app-drawer').align = this.directionDelegate.isRtl() ?
         'right' : 'left';
   },
 });