[Sync] Display the client server traffic log in about:sync.

chrome/browser/resources/sync_internals/traffic.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.
+
+(function() {
+  var trafficToTextButton = document.getElementById('traffic-to-text');
+  var trafficDump = document.getElementById('traffic-dump');
+  trafficToTextButton.addEventListener('click', function(event) {
+    chrome.sync.getClientServerTraffic(printData);
+});
+
+function printData(trafficRecord) {
+  var traffic_data = '';
+  traffic_data += '===\n';
+  traffic_data += 'Client Server Traffic\n';
+  traffic_data += '===\n';
+  traffic_data += JSON.stringify(trafficRecord, null, 2);
+  traffic_data += '\n';
+
+  trafficDump.textContent = traffic_data;
+}
+})();