[Sync] Implement search frontend in chrome://sync-internals.

chrome/browser/resources/sync_internals/chrome_sync.js

 // Copyright (c) 2011 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 chrome = chrome || {};
 // TODO(akalin): Add mocking code for e.g. chrome.send() so that we
 // can test this without rebuilding chrome.
 chrome.sync = chrome.sync || {};
 (function () {
 
@@ skipping 132 matching lines @@
   'getNodesById',
   'getChildNodeIds',
   'findNodesContainingString'
 ];
 
 for (var i = 0; i < syncFunctions.length; ++i) {
   var syncFunction = syncFunctions[i];
   chrome.sync[syncFunction] = makeSyncFunction(syncFunction);
 }
 
+/**
+ * Returns an object which measures elapsed time.
+ */
+chrome.sync.makeTimer = function() {
+  var start = new Date();
+
+  return {
+    /**
+     * @return {number} The number of seconds since the timer was
+     * created.
+     */
+    get elapsedSeconds() {
+      return ((new Date()).getTime() - start.getTime()) / 1000.0;
+    }
+  };
+};
+
 })();