Reland of Use TaskScheduler instead of WorkerPool in BackgroundTaskRunner.cpp

third_party/WebKit/Source/platform/threading/BackgroundTaskRunner.cpp

 // 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 "platform/threading/BackgroundTaskRunner.h"
 
 #include "base/location.h"
-#include "base/threading/worker_pool.h"
+#include "base/task_scheduler/post_task.h"
 #include "public/platform/WebTraceLocation.h"
 
 namespace blink {
 
 void BackgroundTaskRunner::PostOnBackgroundThread(
     const WebTraceLocation& location,
     std::unique_ptr<CrossThreadClosure> closure) {
-  base::WorkerPool::PostTask(
-      location, ConvertToBaseCallback(std::move(closure)), false /* ignored */);
+  base::PostTaskWithTraits(location,
+                           {base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN},
+                           ConvertToBaseCallback(std::move(closure)));
 }
 
 }  // namespace blink