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

chrome/browser/resources/settings/site_settings/usb_devices.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
  * 'usb-devices' is the polymer element for showing the USB Devices category
  * under Site Settings.
  */
 
@@ skipping 19 matching lines @@
   /** @override */
   ready: function() {
     this.fetchUsbDevices_();
   },
 
   /**
    * Fetch the list of USB devices and update the list.
    * @private
    */
   fetchUsbDevices_: function() {
-    this.browserProxy.fetchUsbDevices().then(function(deviceList) {
+    this.browserProxy.fetchUsbDevices().then(deviceList => {
       this.devices_ = deviceList;
-    }.bind(this));
+    });
   },
 
   /**
    * @return {boolean}
    * @private
    */
   hasDevices_: function() {
     return !!(this.devices_ && this.devices_.length);
   },
 
@@ skipping 17 matching lines @@
    * @private
    */
   showMenu_: function(event) {
     this.actionMenuModel_ = event.model.item;
     /** @type {!CrActionMenuElement} */ (this.$$('dialog[is=cr-action-menu]'))
         .showAt(
             /** @type {!Element} */ (
                 Polymer.dom(/** @type {!Event} */ (event)).localTarget));
   }
 });