Add Web Page Replay test to page cycler.

tools/page_cycler/webpagereplay/extension/content.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.
+
+// Hook onload and then add a timeout to send timing information
+// after the onload has completed.
+window.addEventListener('load', function() {
+    window.setTimeout(function() {
+        chrome.extension.sendRequest({
+            "timing": window.performance.timing,
+            "loadTimes": chrome.loadTimes(),
+        });
+    }, 0);
+}, false);