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

chrome/browser/resources/settings/people_page/lock_screen.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-lock-screen' allows the user to change how they unlock their
  * device.
  *
  * Example:
@@ skipping 181 matching lines @@
   /**
    * Overridden from settings.RouteObserverBehavior.
    * @param {!settings.Route} newRoute
    * @param {!settings.Route} oldRoute
    * @protected
    */
   currentRouteChanged: function(newRoute, oldRoute) {
     if (newRoute == settings.routes.LOCK_SCREEN &&
         this.fingerprintUnlockEnabled_ && this.fingerprintBrowserProxy_) {
       this.fingerprintBrowserProxy_.getNumFingerprints().then(
-          function(numFingerprints) {
+          numFingerprints => {
             this.numFingerprints_ = numFingerprints;
-          }.bind(this));
+          });
     }
 
     if (this.shouldAskForPassword_(newRoute)) {
       this.openPasswordPromptDialog_();
     } else if (
         newRoute != settings.routes.FINGERPRINT &&
         oldRoute != settings.routes.FINGERPRINT) {
       // If the user navigated away from the lock screen settings page they will
       // have to re-enter their password. An exception is if they are navigating
       // to or from the fingerprint subpage.
@@ skipping 147 matching lines @@
   /**
    * @param {boolean} easyUnlockEnabled
    * @param {boolean} proximityDetectionAllowed
    * @private
    */
   getShowEasyUnlockToggle_: function(
       easyUnlockEnabled, proximityDetectionAllowed) {
     return easyUnlockEnabled && proximityDetectionAllowed;
   },
 });