Move Task Scheduler Single Thread Task Runners to Dedicated Threads

base/task_scheduler/task_scheduler_impl.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_TASK_SCHEDULER_IMPL_H_
 #define BASE_TASK_SCHEDULER_TASK_SCHEDULER_IMPL_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 12 matching lines @@
 #include "base/threading/thread.h"
 
 namespace base {
 
 class HistogramBase;
 class SchedulerWorkerPoolParams;
 
 namespace internal {
 
 class DelayedTaskManager;
+class SchedulerSingleThreadWorkerPoolManager;
 class TaskTracker;
 
 // Default TaskScheduler implementation. This class is thread-safe.
 class BASE_EXPORT TaskSchedulerImpl : public TaskScheduler {
  public:
   // Creates and returns an initialized TaskSchedulerImpl. CHECKs on failure.
   // |worker_pool_params_vector| describes the worker pools to create.
   // |worker_pool_index_for_traits_callback| returns the index in |worker_pools|
   // of the worker pool in which a task with given traits should run.
   static std::unique_ptr<TaskSchedulerImpl> Create(
@@ skipping 32 matching lines @@
   // Callback invoked when a non-single-thread |sequence| isn't empty after a
   // worker pops a Task from it.
   void ReEnqueueSequenceCallback(scoped_refptr<Sequence> sequence);
 
   Thread service_thread_;
   std::unique_ptr<TaskTracker> task_tracker_;
   std::unique_ptr<DelayedTaskManager> delayed_task_manager_;
   const WorkerPoolIndexForTraitsCallback worker_pool_index_for_traits_callback_;
   std::vector<std::unique_ptr<SchedulerWorkerPoolImpl>> worker_pools_;
 
+  std::unique_ptr<SchedulerSingleThreadWorkerPoolManager>
+      scheduler_single_thread_worker_pool_manager_;
+
 #if DCHECK_IS_ON()
   // Set once JoinForTesting() has returned.
   AtomicFlag join_for_testing_returned_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(TaskSchedulerImpl);
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_TASK_SCHEDULER_TASK_SCHEDULER_IMPL_H_