Adding WebThread and new BlinkPlatformImpl for utility thread.

content/utility/webthread_impl_for_utility_thread.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/utility/webthread_impl_for_utility_thread.h"
+
+namespace content {
+
+WebThreadImplForUtilityThread::WebThreadImplForUtilityThread()
+    : task_runner_(base::MessageLoopProxy::current()),
+      thread_id_(base::PlatformThread::CurrentId()) {
+}
+
+WebThreadImplForUtilityThread::~WebThreadImplForUtilityThread() {
+}
+
+blink::WebScheduler* WebThreadImplForUtilityThread::scheduler() const {
+  NOTIMPLEMENTED();
+  return nullptr;
+}
+
+blink::PlatformThreadId WebThreadImplForUtilityThread::threadId() const {
+  return thread_id_;
+}
+
+base::SingleThreadTaskRunner* WebThreadImplForUtilityThread::TaskRunner()
+    const {
+  return task_runner_.get();
+}
+
+scheduler::SingleThreadIdleTaskRunner*
+WebThreadImplForUtilityThread::IdleTaskRunner() const {
+  NOTIMPLEMENTED();
+  return nullptr;
+}
+
+}  // namespace content