Test page for rendering throughput for canvas arcs

tools/perf/page_sets/tough_canvas_cases/rendering_throughput/bench.js

-// Copyright 2012 The Chromium Authors. All rights reserved.
+// Copyright 2016 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.
 
 var bench = (function() {
   var rafFunc;
   var drawFunc;
 
   function tick() {
     drawFunc();
     rafFunc(tick);
   };
 
   function startAnimation() {
     rafFunc = window.requestAnimationFrame ||
               window.webkitRequestAnimationFrame ||
               window.mozRequestAnimationFrame ||
               window.oRequestAnimationFrame ||
               window.msRequestAnimationFrame;
     rafFunc(tick);
   };
 
   var bench = {};
   bench.run = function(df) {
     drawFunc = df;
     startAnimation();
   };
   return bench;
 })();