Have content/ create and destroy its own threads.

chrome/browser/extensions/extension_install_ui.cc

 // 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.
 
 #include "chrome/browser/extensions/extension_install_ui.h"
 
 #include <map>
 
 #include "base/command_line.h"
 #include "base/file_util.h"
+#include "base/message_loop.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
 #include "base/stringprintf.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/extensions/extension_install_dialog.h"
 #include "chrome/browser/extensions/theme_installed_infobar_delegate.h"
 #include "chrome/browser/infobars/infobar_tab_helper.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/simple_message_box.h"
 #include "chrome/browser/tabs/tab_strip_model.h"
@@ skipping 404 matching lines @@
     bool previous_using_native_theme) {
   Profile* profile = tab_contents->profile();
   return new ThemeInstalledInfoBarDelegate(
       tab_contents->infobar_tab_helper(),
       profile->GetExtensionService(),
       ThemeServiceFactory::GetForProfile(profile),
       new_theme,
       previous_theme_id,
       previous_using_native_theme);
 }