Remove SingleThreadTaskRunner Support from SchedulerWorkerPoolImpl

base/task_scheduler/task_scheduler_impl.cc

 // 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.
 
 #include "base/task_scheduler/task_scheduler_impl.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 31 matching lines @@
 }
 
 void TaskSchedulerImpl::PostDelayedTaskWithTraits(
     const tracked_objects::Location& from_here,
     const TaskTraits& traits,
     const Closure& task,
     TimeDelta delay) {
   // Post |task| as part of a one-off single-task Sequence.
   GetWorkerPoolForTraits(traits)->PostTaskWithSequence(
       MakeUnique<Task>(from_here, task, traits, delay),
-      make_scoped_refptr(new Sequence), nullptr);
+      make_scoped_refptr(new Sequence));
 }
 
 scoped_refptr<TaskRunner> TaskSchedulerImpl::CreateTaskRunnerWithTraits(
     const TaskTraits& traits) {
   return GetWorkerPoolForTraits(traits)->CreateTaskRunnerWithTraits(traits);
 }
 
 scoped_refptr<SequencedTaskRunner>
 TaskSchedulerImpl::CreateSequencedTaskRunnerWithTraits(
     const TaskTraits& traits) {
@@ skipping 128 matching lines @@
   // in |sequence|.
   const TaskTraits traits =
       sequence->PeekTaskTraits().WithPriority(sort_key.priority());
 
   GetWorkerPoolForTraits(traits)->ReEnqueueSequence(std::move(sequence),
                                                     sort_key);
 }
 
 }  // namespace internal
 }  // namespace base