tools/perf/measurements/page_cycler.js

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 (function() {
   6 // The Mozilla DHTML performance tests need to explicitly call a function to
   7 // trigger the next page visit, rather than directly using the onload handler.
   8 // To meet needs of the DHTML performance tests without forking this head.js
   9 // file, use a variable |__install_onload_handler| to indicate whether the
  10 // |__onload| handler should be added to onload event listener.
  11 // Install |__onload| by default if there is no pre-configuration.
  12 if (typeof(__install_onload_handler) == 'undefined')
  13   var __install_onload_handler = true;
  14
  15 // This is the timeout used in setTimeout inside the DHTML tests.  Chrome has
  16 // a much more accurate timer resolution than other browsers do.  This results
  17 // in Chrome running these tests much faster than other browsers.  In order to
  18 // compare Chrome with other browsers on DHTML performance alone, set this
  19 // value to ~15.
  20 var __test_timeout = 0;
  21
  22 function __set_cookie(name, value) {
  23   document.cookie = name + "=" + value + "; path=/";
  24 }
  25
  26 function __onbeforeunload() {
  27   // Call GC twice to cleanup JS heap before starting a new test.
  28   if (window.gc) {
  29     window.gc();
  30     window.gc();
  31   }
  32 }
  33
  34 // The function |__onload| is used by the DHTML tests.
  35 window.__onload = function() {
  36   if (!__install_onload_handler && !performance.timing.loadEventEnd)
  37     return;
  38
  39   var unused = document.body.offsetHeight;  // force layout
  40
  41   window.__pc_load_time = window.performance.now();
  42 };
  43
  44 // The function |__eval_later| now is only used by the DHTML tests.
  45 window.__eval_later = function(expression) {
  46   setTimeout(expression, __test_timeout);
  47 };
  48
  49 if (window.parent == window) {  // Ignore subframes.
  50   window.__pc_load_time = null;
  51   addEventListener("load", __onload);
  52   addEventListener("beforeunload", __onbeforeunload);
  53 }
  54 })();