Clean up perftesthelper.js style

tools/perf/page_sets/tough_animation_cases/resources/perf_test_helper.js

+// Copyright 2014 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.
+(function() {
+'use strict';
+
+if (window.PerfTestHelper) {
+  return;
+}
+window.PerfTestHelper = {};
+
+var randomSeed = 3384413;
+var mask = 0xffffffff;
+window.PerfTestHelper.random = function() {
+  var temp = randomSeed;
+  // Robert Jenkins' 32 bit integer hash function.
+  temp = ((temp + 0x7ed55d16) + (temp << 12)) & mask;
+  temp = ((temp ^ 0xc761c23c) ^ (temp >>> 19)) & mask;
+  temp = ((temp + 0x165667b1) + (temp << 5)) & mask;
+  temp = ((temp + 0xd3a2646c) ^ (temp << 9)) & mask;
+  temp = ((temp + 0xfd7046c5) + (temp << 3)) & mask;
+  temp = ((temp ^ 0xb55a4f09) ^ (temp >>> 16)) & mask;
+  randomSeed = temp;
+  return (randomSeed & 0xfffffff) / 0x10000000;
+};
+
+window.PerfTestHelper.getParameter = function(parameter) {
+  var match = new RegExp(parameter + '=([^&]*)').exec(window.location.search);
+  if (match) {
+    return match[1];
+  }
+  return null;
+};
+
+window.PerfTestHelper.getN = function(defaultN) {
+  var match = PerfTestHelper.getParameter('N');
+  if (match) {
+    var n = Number(match);
+    if (isNaN(n)) {
+      throw 'Invalid N value: ' + match;
+    }
+    return n;
+  }
+  if (typeof defaultN === 'undefined') {
+    throw 'Default N value required';
+  }
+  return defaultN;
+};
+
+window.PerfTestHelper.signalReady = function() {
+  requestAnimationFrame(function() {
+    // FIXME: We must wait at least two frames before
+    // measuring to allow the GC to clean up the
+    // previous test.
+    requestAnimationFrame(function() {
+      window.measurementReady = true;
+    });
+  });
+};
+
+})();