Revert of Remove header dependencies from sequence_checker.h to sequenced_worker_pool.h

ios/web/shell/shell_url_request_context_getter.mm

 // 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 "ios/web/shell/shell_url_request_context_getter.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/base_paths.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/path_service.h"
-#include "base/threading/sequenced_worker_pool.h"
 #import "ios/net/cookies/cookie_store_ios_persistent.h"
 #import "ios/web/public/web_client.h"
 #include "ios/web/public/web_thread.h"
 #include "ios/web/shell/shell_network_delegate.h"
 #include "net/base/cache_type.h"
 #include "net/cert/cert_verifier.h"
 #include "net/cert/ct_policy_enforcer.h"
 #include "net/cert/multi_log_ct_verifier.h"
 #include "net/dns/host_resolver.h"
 #include "net/extras/sqlite/sqlite_persistent_cookie_store.h"
@@ skipping 141 matching lines @@
 
   return url_request_context_.get();
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
 ShellURLRequestContextGetter::GetNetworkTaskRunner() const {
   return network_task_runner_;
 }
 
 }  // namespace web