Revert of Revert of Add a WorkerScheduler and a WebThreadImplForWorker

content/child/scheduler/webthread_impl_for_worker_scheduler.cc

+// 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 "content/child/scheduler/webthread_impl_for_worker_scheduler.h"
+
+#include "base/bind.h"
+#include "base/synchronization/waitable_event.h"
+#include "content/child/scheduler/scheduler_message_loop_delegate.h"
+#include "content/child/scheduler/worker_scheduler_impl.h"
+#include "third_party/WebKit/public/platform/WebTraceLocation.h"
+
+namespace content {
+
+WebThreadImplForWorkerScheduler::WebThreadImplForWorkerScheduler(
+    const char* name)
+    : thread_(new base::Thread(name)) {
+  thread_->Start();
+
+  base::WaitableEvent completion(false, false);
+  thread_->message_loop()->PostTask(
+      FROM_HERE, base::Bind(&WebThreadImplForWorkerScheduler::InitOnThread,
+                            base::Unretained(this), &completion));
+  completion.Wait();
+}
+
+WebThreadImplForWorkerScheduler::~WebThreadImplForWorkerScheduler() {
+  base::WaitableEvent completion(false, false);
+  // We need to post the shutdown task on the scheduler's task queue or tasks
+  // posted on the worker scheduler may not get run when the thread is deleted.
+  TaskRunner()->PostTask(
+      FROM_HERE, base::Bind(&WebThreadImplForWorkerScheduler::ShutDownOnThread,
+                            base::Unretained(this), &completion));
+  completion.Wait();
+
+  thread_->Stop();
+}
+
+void WebThreadImplForWorkerScheduler::InitOnThread(
+    base::WaitableEvent* completion) {
+  worker_scheduler_ = WorkerScheduler::Create(thread_->message_loop());
+  worker_scheduler_->Init();
+  task_runner_ = worker_scheduler_->DefaultTaskRunner();
+  idle_task_runner_ = worker_scheduler_->IdleTaskRunner();
+  completion->Signal();
+}
+
+void WebThreadImplForWorkerScheduler::ShutDownOnThread(
+    base::WaitableEvent* completion) {
+  task_runner_ = nullptr;
+  idle_task_runner_ = nullptr;
+  worker_scheduler_.reset(nullptr);
+  completion->Signal();
+}
+
+blink::PlatformThreadId WebThreadImplForWorkerScheduler::threadId() const {
+  return thread_->thread_id();
+}
+
+base::MessageLoop* WebThreadImplForWorkerScheduler::MessageLoop() const {
+  // As per WebThreadImpl::MessageLoop()
+  return nullptr;
+}
+
+base::SingleThreadTaskRunner* WebThreadImplForWorkerScheduler::TaskRunner()
+    const {
+  return task_runner_.get();
+}
+
+SingleThreadIdleTaskRunner* WebThreadImplForWorkerScheduler::IdleTaskRunner()
+    const {
+  return idle_task_runner_.get();
+}
+
+void WebThreadImplForWorkerScheduler::AddTaskObserverInternal(
+    base::MessageLoop::TaskObserver* observer) {
+  worker_scheduler_->AddTaskObserver(observer);
+}
+
+void WebThreadImplForWorkerScheduler::RemoveTaskObserverInternal(
+    base::MessageLoop::TaskObserver* observer) {
+  worker_scheduler_->RemoveTaskObserver(observer);
+}
+
+}  // namespace content