Use TaskScheduler instead of SequencedWorkerPool in chrome_cookie_store_ios_client.mm.

ios/chrome/browser/net/chrome_cookie_store_ios_client.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/chrome/browser/net/chrome_cookie_store_ios_client.h"
 
 #include "base/logging.h"
-#include "base/threading/sequenced_worker_pool.h"
+#include "base/task_scheduler/post_task.h"
 #import "ios/chrome/browser/browsing_data/browsing_data_change_listening.h"
 #include "ios/web/public/web_thread.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 ChromeCookieStoreIOSClient::ChromeCookieStoreIOSClient(
     id<BrowsingDataChangeListening> browsing_data_change_listener)
     : browsing_data_change_listener_(browsing_data_change_listener) {
   DCHECK(browsing_data_change_listener);
   DCHECK_CURRENTLY_ON(web::WebThread::IO);
 }
 
 void ChromeCookieStoreIOSClient::DidChangeCookieStorage() const {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   [browsing_data_change_listener_ didChangeCookieStorage];
 }
 
 scoped_refptr<base::SequencedTaskRunner>
 ChromeCookieStoreIOSClient::GetTaskRunner() const {
   DCHECK(thread_checker_.CalledOnValidThread());
-
-  base::SequencedWorkerPool* pool = web::WebThread::GetBlockingPool();
-  return pool->GetSequencedTaskRunner(pool->GetSequenceToken()).get();
+  return base::CreateSequencedTaskRunnerWithTraits(
+      {base::MayBlock(), base::TaskPriority::BACKGROUND});
 }