Revert of Revert of Add a WorkerScheduler and a WebThreadImplForWorker

content/child/scheduler/null_worker_scheduler.cc

+// 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 "content/child/scheduler/null_worker_scheduler.h"
+
+#include "base/bind.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "content/child/scheduler/null_idle_task_runner.h"
+
+namespace content {
+
+NullWorkerScheduler::NullWorkerScheduler()
+    : task_runner_(base::MessageLoopProxy::current()),
+      idle_task_runner_(new NullIdleTaskRunner()) {
+}
+
+NullWorkerScheduler::~NullWorkerScheduler() {
+}
+
+scoped_refptr<base::SingleThreadTaskRunner>
+NullWorkerScheduler::DefaultTaskRunner() {
+  return task_runner_;
+}
+
+scoped_refptr<SingleThreadIdleTaskRunner>
+NullWorkerScheduler::IdleTaskRunner() {
+  return idle_task_runner_;
+}
+
+void NullWorkerScheduler::AddTaskObserver(
+    base::MessageLoop::TaskObserver* task_observer) {
+  base::MessageLoop::current()->AddTaskObserver(task_observer);
+}
+
+void NullWorkerScheduler::RemoveTaskObserver(
+    base::MessageLoop::TaskObserver* task_observer) {
+  base::MessageLoop::current()->RemoveTaskObserver(task_observer);
+}
+
+bool NullWorkerScheduler::CanExceedIdleDeadlineIfRequired() const {
+  return false;
+}
+
+void NullWorkerScheduler::Init() {
+}
+
+void NullWorkerScheduler::Shutdown() {
+}
+
+}  // namespace content