Update references to the extension messaging APIs to point to the "runtime"

tools/page_cycler/webpagereplay/extension/start.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.
 
 document.cookie = "__navigated_to_report=0; path=/";
 document.cookie = "__pc_done=0; path=/";
 document.cookie = "__pc_timings=; path=/";
 
 function dirname(path) {
   var match = path.match(/(.*)\//);
@@ skipping 53 matching lines @@
   if (!config["shouldStart"]) {
     status_element.textContent =
         "Press 'Start' to continue (or load this page with 'auto=1').";
     return;
   }
 
   try {
     var reportDir = dirname(dirname(window.location.pathname)) + "/common";
     config["reportUrl"] = "file://" + reportDir + "/report.html";
     config["isRecordMode"] = isRecordMode;
-    var port = chrome.extension.connect();
+    var port = chrome.runtime.connect();
     port.postMessage({message: "start", benchmark: config});
     console.log("sending start message: page count, " +
                 config["pageSets"].length);
   } catch(err) {
     console.log("TryStart retrying after exception: " + err);
     status_element.textContent = "Exception: " + err;
     setTimeout(TryStart, 1000);
     return;
   }
   status_element.textContent = "STARTING";
 }
 
 // We wait before starting the test just to let chrome warm up better.
 setTimeout(TryStart, 250);