Reduce failsafe time for animation events. This makes the lock-time more consistent.

ui/webui/resources/js/util.js

 // Copyright (c) 2012 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.
 
 // <include src="assert.js">
 
 /**
  * Alias for document.getElementById. Found elements must be HTMLElements.
  * @param {string} id The ID of the element to find.
  * @return {HTMLElement} The found element or null if not found.
@@ skipping 356 matching lines @@
   var elm = document.createElement(type);
   elm.className = className;
   return elm;
 }
 
 /**
  * webkitTransitionEnd does not always fire (e.g. when animation is aborted
  * or when no paint happens during the animation). This function sets up
  * a timer and emulate the event if it is not fired when the timer expires.
  * @param {!HTMLElement} el The element to watch for webkitTransitionEnd.
- * @param {number} timeOut The maximum wait time in milliseconds for the
- *     webkitTransitionEnd to happen.
+ * @param {number} opt_timeOut The maximum wait time in milliseconds for the

[xiyuan, 2016/03/18 18:23:52]

nit: number -> number=

[jdufault, 2016/03/25 23:36:56]

Done.

+ *     webkitTransitionEnd to happen. If not specified, it is fetched from |el|
+ *     using the transitionDuration style value.
  */
-function ensureTransitionEndEvent(el, timeOut) {
+function ensureTransitionEndEvent(el, opt_timeOut) {
+  if (opt_timeOut === undefined) {
+    var style = getComputedStyle(el);
+    opt_timeOut = parseFloat(style.transitionDuration) * 1000;
+
+    // Give an additional 50ms buffer for the animation to complete.
+    opt_timeOut += 50;
+  }
+
   var fired = false;
   el.addEventListener('webkitTransitionEnd', function f(e) {
     el.removeEventListener('webkitTransitionEnd', f);
     fired = true;
   });
   window.setTimeout(function() {
     if (!fired)
       cr.dispatchSimpleEvent(el, 'webkitTransitionEnd', true);
-  }, timeOut);
+  }, opt_timeOut);
 }
 
 /**
  * Alias for document.scrollTop getter.
  * @param {!HTMLDocument} doc The document node where information will be
  *     queried from.
  * @return {number} The Y document scroll offset.
  */
 function scrollTopForDocument(doc) {
   return doc.documentElement.scrollTop || doc.body.scrollTop;
@@ skipping 58 matching lines @@
 }
 
 /**
  * Quote a string so it can be used in a regular expression.
  * @param {string} str The source string.
  * @return {string} The escaped string.
  */
 function quoteString(str) {
   return str.replace(/([\\\.\+\*\?\[\^\]\$\(\)\{\}\=\!\<\>\|\:])/g, '\\$1');
 }