Fix purify error for DOM UI unit test.

chrome/browser/dom_ui/new_tab_ui.cc

 // Copyright (c) 2006-2008 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.
 
 #include "build/build_config.h"
 
 #include "chrome/browser/dom_ui/new_tab_ui.h"
 
 #include "base/histogram.h"
 #include "base/string_piece.h"
@@ skipping 1035 matching lines @@
     AddMessageHandler(new RecentlyBookmarkedHandler(this));
     AddMessageHandler(new RecentlyClosedTabsHandler(this));
     AddMessageHandler(new HistoryHandler(this));
     AddMessageHandler(new MetricsHandler(this));
 #ifdef CHROME_PERSONALIZATION
     if (!Personalization::IsP13NDisabled()) {
       AddMessageHandler(Personalization::CreateNewTabPageHandler(this));
     }
 #endif
 
-    NewTabHTMLSource* html_source = new NewTabHTMLSource();
-
     // In testing mode there may not be an I/O thread.
     if (g_browser_process->io_thread()) {
+      NewTabHTMLSource* html_source = new NewTabHTMLSource();
       g_browser_process->io_thread()->message_loop()->PostTask(FROM_HERE,
           NewRunnableMethod(&chrome_url_data_manager,
               &ChromeURLDataManager::AddDataSource,
               html_source));
     }
   }
 }
 
 NewTabUI::~NewTabUI() {
 }