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

chrome/browser/loader/chrome_resource_dispatcher_host_delegate_browsertest.cc

 // Copyright 2014 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/loader/chrome_resource_dispatcher_host_delegate.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <memory>
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/path_service.h"
 #include "base/run_loop.h"
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
 #include "base/test/scoped_command_line.h"
+#include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/download/download_browsertest.h"
 #include "chrome/browser/loader/chrome_navigation_data.h"
 #include "chrome/browser/policy/cloud/policy_header_service_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/test/base/in_process_browser_test.h"
@@ skipping 596 matching lines @@
   DownloadTestObserverNotInProgress download_observer(
       content::BrowserContext::GetDownloadManager(browser()->profile()), 1);
   download_observer.StartObserving();
   ui_test_utils::NavigateToURL(browser(), embedded_test_server()->GetURL(
                                               "/download-anchor-attrib.html"));
   download_observer.WaitForFinished();
   EXPECT_EQ(1,
             GetTimesStandardThrottlesAddedForURL(
                 embedded_test_server()->GetURL("/anchor_download_test.png")));
 }