Use the unprefixed Pointer Lock API

chrome/test/data/extensions/platform_apps/web_view/pointer_lock/guest.js

 // Copyright (c) 2013 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.
 
 // See chrome/browser/extensions/web_view_interactive_browsertest.cc
 // (WebViewInteractiveTest, PointerLock) for documentation on this test.
 
 function LockMouse(element) {
-  element.requestPointerLock = element.webkitRequestPointerLock;
+  element.requestPointerLock = element.requestPointerLock;
   element.requestPointerLock();
 }
 var first_lock = true;
-document.onwebkitpointerlockchange = function() {
-  if (document.webkitPointerLockElement) {
+document.onpointerlockchange = function() {
+  if (document.pointerLockElement) {
     if (first_lock) {
       console.log('locked');
       setTimeout(function() { embedder.postMessage('locked', '*'); }, 500);
     } else {
       console.log('deleting...');
       setTimeout(function() { embedder.postMessage('delete me', '*'); }, 500);
     }
     first_lock = false;
   } else {
     console.log('unlocked');
     embedder.postMessage('unlocked', '*');
   }
 }
 
-document.onwebkitpointerlockerror = function() {
+document.onpointerlockerror = function() {
   console.log('lock error', '*');
   setTimeout(function() {  embedder.postMessage('lock error', '*'); }, 1000);
 }
 
 var embedder = null;
 window.addEventListener('message', function(e) {
   embedder = e.source;
   embedder.postMessage('connected', '*');
 });
 
@@ skipping 14 matching lines @@
 
 document.getElementById('button1').addEventListener('click', function (e) {
   console.log('click captured, locking mouse');
   LockMouse(locktarget1);
 }, false);
 
 document.getElementById('button2').addEventListener('click', function (e) {
   console.log('clicked button 2');
   embedder.postMessage('clicked', '*');
 }, false);