Revert of Revert of Add a WorkerScheduler and a WebThreadImplForWorker

content/renderer/scheduler/webthread_impl_for_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/renderer/scheduler/webthread_impl_for_scheduler.h"
-
-#include "content/renderer/scheduler/renderer_scheduler.h"
-#include "third_party/WebKit/public/platform/WebTraceLocation.h"
-
-namespace content {
-
-WebThreadImplForScheduler::WebThreadImplForScheduler(
-    RendererScheduler* scheduler)
-    : task_runner_(scheduler->DefaultTaskRunner()),
-      scheduler_(scheduler),
-      thread_id_(base::PlatformThread::CurrentId()) {
-}
-
-WebThreadImplForScheduler::~WebThreadImplForScheduler() {
-}
-
-blink::PlatformThreadId WebThreadImplForScheduler::threadId() const {
-  return thread_id_;
-}
-
-base::MessageLoop* WebThreadImplForScheduler::MessageLoop() const {
-  DCHECK(isCurrentThread());
-  return base::MessageLoop::current();
-}
-
-base::SingleThreadTaskRunner* WebThreadImplForScheduler::TaskRunner() const {
-  return task_runner_.get();
-}
-
-void WebThreadImplForScheduler::AddTaskObserverInternal(
-    base::MessageLoop::TaskObserver* observer) {
-  scheduler_->AddTaskObserver(observer);
-}
-
-void WebThreadImplForScheduler::RemoveTaskObserverInternal(
-    base::MessageLoop::TaskObserver* observer) {
-  scheduler_->RemoveTaskObserver(observer);
-}
-
-}  // namespace content