Add missing #include around sequenced_worker_pool.h in //chrome

chrome/browser/ntp_tiles/chrome_popular_sites_factory.cc

 // 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.
 
 #include "chrome/browser/ntp_tiles/chrome_popular_sites_factory.h"
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
 #include "base/path_service.h"
+#include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/search_engines/template_url_service_factory.h"
 #include "chrome/common/chrome_paths.h"
 #include "components/ntp_tiles/popular_sites_impl.h"
 #include "components/safe_json/safe_json_parser.h"
 #include "content/public/browser/browser_thread.h"
 
 std::unique_ptr<ntp_tiles::PopularSites>
 ChromePopularSitesFactory::NewForProfile(Profile* profile) {
   base::FilePath directory;  // remains empty if PathService::Get() fails.
   PathService::Get(chrome::DIR_USER_DATA, &directory);
   return base::MakeUnique<ntp_tiles::PopularSitesImpl>(
       content::BrowserThread::GetBlockingPool(), profile->GetPrefs(),
       TemplateURLServiceFactory::GetForProfile(profile),
       g_browser_process->variations_service(), profile->GetRequestContext(),
       directory, base::Bind(safe_json::SafeJsonParser::Parse));
 }