MD Settings: Convert all usages of .bind(this) to use ES6 arrow function.

chrome/browser/resources/settings/search_engines_page/search_engines_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-search-engines-page' is the settings page
  * containing search engines settings.
  */
 Polymer({
   is: 'settings-search-engines-page',
@@ skipping 87 matching lines @@
     this.extensions = searchEnginesInfo['extensions'];
   },
 
   /**
    * @param {!Event} e
    * @private
    */
   onAddSearchEngineTap_: function(e) {
     e.preventDefault();
     this.showAddSearchEngineDialog_ = true;
-    this.async(function() {
+    this.async(() => {
       var dialog = this.$$('settings-search-engine-dialog');
       // Register listener to detect when the dialog is closed. Flip the boolean
       // once closed to force a restamp next time it is shown such that the
       // previous dialog's contents are cleared.
-      dialog.addEventListener('close', function() {
+      dialog.addEventListener('close', () => {
         this.showAddSearchEngineDialog_ = false;
         cr.ui.focusWithoutInk(assert(this.$.addSearchEngine));
-      }.bind(this));
-    }.bind(this));
+      });
+    });
   },
 
   /** @private */
   computeShowExtensionsList_: function() {
     return this.extensions.length > 0;
   },
 });