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      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 })();