Add Web Page Replay test to page cycler.

tools/page_cycler/common/head.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.
 
 var __c = ""; // that's good enough for me.
 var __td;
 var __tf;
 var __tl;
 var __iterations;
 var __cycle;
 var __results = false;
 var __page;
 var __TIMEOUT = 15;
 function __get_cookie(name) {
   var cookies = document.cookie.split("; ");
   for (var i = 0; i < cookies.length; ++i) {
     var t = cookies[i].split("=");
     if (t[0] == name && t[1])
       return t[1];
   }
   return "";
 }
 function __pages() {  // fetch lazily
   if (!("data" in this))
     this.data = __get_cookie("__pc_pages").split(",");
   return this.data;
 }
 function __get_timings() {
-  if (sessionStorage == null)
+  if (sessionStorage != null &&
+      sessionStorage.getItem("__pc_timings") != null) {
+    return sessionStorage["__pc_timings"];
+  } else {
     return __get_cookie("__pc_timings");
-  else {
-    if (sessionStorage.getItem("__pc_timings") == null)
-      return "";
-    else
-      return sessionStorage["__pc_timings"];
   }
 }
 function __set_timings(timings) {
   if (sessionStorage == null)
     document.cookie = "__pc_timings=" + timings + "; path=/";
   else
     sessionStorage["__pc_timings"]=timings;
 }
 function __ontimeout() {
   var doc;
@@ skipping 75 matching lines @@
   __te = te;
   __tf = tf;  // record t-fudge
 
   setTimeout("__ontimeout()", __TIMEOUT);
 }
 
 if (window.attachEvent)
   window.attachEvent("onload", __onload);
 else
   addEventListener("load", __onload, false);