DESIGN DISCUSSION ONLY Task Scheduler Single Thread Task Runner Manager for Dedicated Threads per S…

base/task_scheduler/delayed_task_manager.h

 // Copyright 2016 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 BASE_TASK_SCHEDULER_DELAYED_TASK_MANAGER_H_
 #define BASE_TASK_SCHEDULER_DELAYED_TASK_MANAGER_H_
 
 #include <memory>
 
 #include "base/base_export.h"
+#include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/time/time.h"
 
 namespace base {
 
 class TaskRunner;
 
 namespace internal {
 
-class SchedulerWorker;
-class SchedulerWorkerPool;
-class Sequence;
 struct Task;
 
-// A DelayedTaskManager forwards Tasks to a SchedulerWorkerPool when they become
-// ripe for execution. This class is thread-safe.
+// The DelayedTaskManager forwards tasks to various scheduler components when
+// they become ripe for execution. This class is thread-safe.
 class BASE_EXPORT DelayedTaskManager {
  public:
+  // Posts |task| for execution immediately.
+  using PostTaskNowCallback = Callback<void(std::unique_ptr<Task> task)>;
+
   // |service_thread_task_runner| posts tasks to the TaskScheduler service
   // thread.
   explicit DelayedTaskManager(
       scoped_refptr<TaskRunner> service_thread_task_runner);
   ~DelayedTaskManager();
 
-  // Posts |task|. The task will be forwarded to |worker_pool| with |sequence|
-  // and |worker| when it becomes ripe for execution. |worker| is a
-  // SchedulerWorker owned by |worker_pool| or nullptr.
-  //
-  // TODO(robliao): Find a concrete way to manage the memory of |worker| and
-  // |worker_pool|. These objects are never deleted in production, but it is
-  // better not to spread this assumption throughout the scheduler.
+  // Calls |post_task_now_callback| with |task| when |task| is ripe for
+  // execution.
   void AddDelayedTask(std::unique_ptr<Task> task,
-                      scoped_refptr<Sequence> sequence,
-                      SchedulerWorker* worker,
-                      SchedulerWorkerPool* worker_pool);
+                      const PostTaskNowCallback& post_task_now_callback);
 
  private:
   const scoped_refptr<TaskRunner> service_thread_task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(DelayedTaskManager);
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_TASK_SCHEDULER_DELAYED_TASK_MANAGER_H_