Revert of Worker: Introduce per-global-scope task scheduler

third_party/WebKit/Source/platform/scheduler/child/worker_global_scope_scheduler.cc

-// Copyright 2017 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/scheduler/child/worker_global_scope_scheduler.h"
-
-#include "platform/scheduler/child/worker_scheduler.h"
-
-namespace blink {
-namespace scheduler {
-
-WorkerGlobalScopeScheduler::WorkerGlobalScopeScheduler(
-    WorkerScheduler* worker_scheduler) {
-  scoped_refptr<TaskQueue> task_queue =
-      worker_scheduler->CreateUnthrottledTaskRunner(
-          TaskQueue::QueueType::UNTHROTTLED);
-  unthrottled_task_runner_ = WebTaskRunnerImpl::Create(std::move(task_queue));
-}
-
-WorkerGlobalScopeScheduler::~WorkerGlobalScopeScheduler() {
-#if DCHECK_IS_ON()
-  DCHECK(is_disposed_);
-#endif
-}
-
-void WorkerGlobalScopeScheduler::Dispose() {
-  unthrottled_task_runner_->GetTaskQueue()->UnregisterTaskQueue();
-#if DCHECK_IS_ON()
-  is_disposed_ = true;
-#endif
-}
-
-}  // namespace scheduler
-}  // namespace blink