Revert of Remove race in DeclarativeContentApiTest.RulesPersistence test

chrome/test/data/extensions/api_test/declarative_content/persistence/background.js

 // Copyright 2015 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 hostPrefix = chrome.extension.inIncognitoContext ? 'test_split' :
     'test_normal';
 
 var rule = {
   conditions: [
     new chrome.declarativeContent.PageStateMatcher({
@@ skipping 18 matching lines @@
 // chrome.storage.local, but the onInstalled event only gets sent for the
 // non-incognito side of the extension in split incognito mode.
 var key = chrome.extension.inIncognitoContext ? "split" : "normal";
 chrome.storage.local.get(key, function(items) {
   if (!(key in items)) {
     chrome.declarativeContent.onPageChanged.addRules([rule], function() {
       items[key] = "added";
       chrome.storage.local.set(items, sendMessage.bind(null, "ready"));
     });
   } else {
-    sendMessage("second run ready");
+    sendMessage(sendMessage("second run ready"));
   }
 });