content: Add RendererScheduler.

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/memory/weak_ptr.h"
+#include "base/single_thread_task_runner.h"
+#include "base/time/time.h"
+
+namespace content {
+
+class IdleTaskDeadlineSupplier;
+
+// An IdleTaskRunner 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 executed. 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> task_runner,
+      base::WeakPtr<IdleTaskDeadlineSupplier> deadline_supplier);
+
+  virtual void PostIdleTask(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::TaskRunner> task_runner_;
+  base::WeakPtr<IdleTaskDeadlineSupplier> deadline_supplier_;
+};
+
+class IdleTaskDeadlineSupplier {
+ public:
+  // Returns the deadline by which an idle task should finish by.
+  virtual base::TimeTicks CurrentIdleTaskDeadline() const = 0;
+
+ protected:
+  virtual ~IdleTaskDeadlineSupplier();
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_SCHEDULER_SINGLE_THREAD_IDLE_TASK_RUNNER_H_