TaskScheduler: Replace the SchedulerServiceThread with a base::Thread.

base/task_scheduler/scheduler_worker_pool.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_SCHEDULER_WORKER_POOL_H_
 #define BASE_TASK_SCHEDULER_SCHEDULER_WORKER_POOL_H_
 
 #include <memory>
 
 #include "base/base_export.h"
@@ skipping 25 matching lines @@
   // be used to put |sequence| back into a queue after running a Task from it.
   // The thread that calls this doesn't have to belong to this
   // SchedulerWorkerPool.
   virtual void ReEnqueueSequence(scoped_refptr<Sequence> sequence,
                                  const SequenceSortKey& sequence_sort_key) = 0;
 
   // Posts |task| to be executed by this SchedulerWorkerPool as part of
   // |sequence|. If |worker| is non-null, |task| will be scheduled to run on it
   // specifically (note: |worker| must be owned by this SchedulerWorkerPool);
   // otherwise, |task| will be added to the pending shared work. |task| won't be
-  // executed before its delayed run time, if any. Returns true if |task| is
-  // posted.
+  // executed before its |delay| expires. Returns true if |task| is posted.
   virtual bool PostTaskWithSequence(std::unique_ptr<Task> task,
                                     scoped_refptr<Sequence> sequence,
-                                    SchedulerWorker* worker) = 0;
+                                    SchedulerWorker* worker,
+                                    TimeDelta delay) = 0;
 
   // Posts |task| to be executed by this SchedulerWorkerPool as part of
   // |sequence|. If |worker| is non-null, |task| will be scheduled to run on it
   // specifically (note: |worker| must be owned by this SchedulerWorkerPool);
   // otherwise, |task| will be added to the pending shared work. This must only
   // be called after |task| has gone through PostTaskWithSequence() and after
   // |task|'s delayed run time.
   virtual void PostTaskWithSequenceNow(std::unique_ptr<Task> task,
                                        scoped_refptr<Sequence> sequence,
                                        SchedulerWorker* worker) = 0;
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_TASK_SCHEDULER_SCHEDULER_WORKER_POOL_H_