Introduce a SchedulerHelper in content/child/scheduler

content/renderer/scheduler/single_thread_idle_task_runner.h

-// 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.
-
-#ifndef CONTENT_RENDERER_SCHEDULER_SINGLE_THREAD_IDLE_TASK_RUNNER_H_
-#define CONTENT_RENDERER_SCHEDULER_SINGLE_THREAD_IDLE_TASK_RUNNER_H_
-
-#include "base/bind.h"
-#include "base/callback.h"
-#include "base/memory/ref_counted.h"
-#include "base/single_thread_task_runner.h"
-#include "base/time/time.h"
-
-namespace content {
-
-// A SingleThreadIdleTaskRunner is a task runner for running idle tasks. Idle
-// tasks have an unbound argument which is bound to a deadline
-// (in base::TimeTicks) when they are run. The idle task is expected to
-// complete by this deadline.
-class SingleThreadIdleTaskRunner
-    : public base::RefCountedThreadSafe<SingleThreadIdleTaskRunner> {
- public:
-  typedef base::Callback<void(base::TimeTicks)> IdleTask;
-
-  SingleThreadIdleTaskRunner(
-      scoped_refptr<base::SingleThreadTaskRunner> idle_priority_task_runner,
-      scoped_refptr<base::SingleThreadTaskRunner> after_wakeup_task_runner,
-      base::Callback<void(base::TimeTicks*)> deadline_supplier);
-
-  virtual void PostIdleTask(const tracked_objects::Location& from_here,
-                            const IdleTask& idle_task);
-
-  virtual void PostNonNestableIdleTask(
-      const tracked_objects::Location& from_here,
-      const IdleTask& idle_task);
-
-  virtual void PostIdleTaskAfterWakeup(
-      const tracked_objects::Location& from_here,
-      const IdleTask& idle_task);
-
-  bool RunsTasksOnCurrentThread() const;
-
- protected:
-  virtual ~SingleThreadIdleTaskRunner();
-
- private:
-  friend class base::RefCountedThreadSafe<SingleThreadIdleTaskRunner>;
-
-  void RunTask(IdleTask idle_task);
-
-  scoped_refptr<base::SingleThreadTaskRunner> idle_priority_task_runner_;
-  scoped_refptr<base::SingleThreadTaskRunner> after_wakeup_task_runner_;
-  base::Callback<void(base::TimeTicks*)> deadline_supplier_;
-  DISALLOW_COPY_AND_ASSIGN(SingleThreadIdleTaskRunner);
-};
-
-}  // namespace content
-
-#endif  // CONTENT_RENDERER_SCHEDULER_SINGLE_THREAD_IDLE_TASK_RUNNER_H_