Introduce a SchedulerHelper in content/child/scheduler

content/renderer/scheduler/null_renderer_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/renderer/scheduler/null_renderer_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 {
 
-namespace {
-
-class NullIdleTaskRunner : public SingleThreadIdleTaskRunner {
- public:
-  NullIdleTaskRunner();
-  void PostIdleTask(const tracked_objects::Location& from_here,
-                    const IdleTask& idle_task) override;
-
- protected:
-  ~NullIdleTaskRunner() override;
-};
-
-}  // namespace
-
-NullIdleTaskRunner::NullIdleTaskRunner()
-    : SingleThreadIdleTaskRunner(nullptr,
-                                 nullptr,
-                                 base::Callback<void(base::TimeTicks*)>()) {
-}
-
-NullIdleTaskRunner::~NullIdleTaskRunner() {
-}
-
-void NullIdleTaskRunner::PostIdleTask(
-    const tracked_objects::Location& from_here,
-    const IdleTask& idle_task) {
-}
-
 NullRendererScheduler::NullRendererScheduler()
     : task_runner_(base::MessageLoopProxy::current()),
       idle_task_runner_(new NullIdleTaskRunner()) {
 }
 
 NullRendererScheduler::~NullRendererScheduler() {
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
 NullRendererScheduler::DefaultTaskRunner() {
@@ skipping 50 matching lines @@
 
 void NullRendererScheduler::RemoveTaskObserver(
     base::MessageLoop::TaskObserver* task_observer) {
   base::MessageLoop::current()->RemoveTaskObserver(task_observer);
 }
 
 void NullRendererScheduler::Shutdown() {
 }
 
 }  // namespace content