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

chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.js

 // Copyright 2016 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-cups-add-printer-dialog' includes multiple dialogs to
  * set up a new CUPS printer.
  * Subdialogs include:
  * - 'add-printer-discovery-dialog' is a dialog showing discovered printers on
  *   the network that are available for setup.
@@ skipping 539 matching lines @@
    *     corresponding to the |toDialog|.
    * @private
    */
   switchDialog_: function(fromDialog, toDialog, domIfBooleanName) {
     this.previousDialog_ = fromDialog;
     this.currentDialog_ = toDialog;
 
     this.set(domIfBooleanName, true);
     this.async(function() {
       var dialog = this.$$(toDialog);
-      dialog.addEventListener('close', function() {
+      dialog.addEventListener('close', () => {
         this.set(domIfBooleanName, false);
-      }.bind(this));
+      });
     });
   },
 
   /**
    * @param {boolean} success
    * @param {string} printerName
    * @private
    */
   onAddPrinter_: function(success, printerName) {
     this.$$('add-printer-configuring-dialog').close();
     if (success)
       return;
 
     if (this.previousDialog_ == AddPrinterDialogs.MANUFACTURER) {
       this.setupFailed = true;
     }
   },
 });