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(

[Sami, 2015/04/13 17:38:49]

In other words this shutdown task mustn't be allowed to bypass the things that
have already been queued through the scheduler? If the message loop was routed
through the scheduler then we wouldn't need this, but this lgtm for now.

+      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