Implement PostDelayedTaskAt for guaranteed timer ordering

components/scheduler/child/task_queue.h

+// 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.
+
+#ifndef COMPONENTS_SCHEDULER_CHILD_TASK_QUEUE_H_
+#define COMPONENTS_SCHEDULER_CHILD_TASK_QUEUE_H_
+
+#include "base/single_thread_task_runner.h"
+#include "components/scheduler/scheduler_export.h"
+
+namespace scheduler {
+
+class SCHEDULER_EXPORT TaskQueue : public base::SingleThreadTaskRunner {
+ public:
+  TaskQueue() {}
+
+  // Post a delayed task at an absolute desired run time instead of a time
+  // delta from the current time.
+  virtual bool PostDelayedTaskAt(const tracked_objects::Location& from_here,
+                                 const base::Closure& task,
+                                 base::TimeTicks desired_run_time) = 0;
+
+ protected:
+  ~TaskQueue() override {}
+
+  DISALLOW_COPY_AND_ASSIGN(TaskQueue);
+};
+
+}  // namespace scheduler
+
+#endif  // COMPONENTS_SCHEDULER_CHILD_TASK_QUEUE_H_