TaskScheduler [11] Support ExecutionMode::SINGLE_THREADED.

base/task_scheduler/scheduler_thread_pool_interface.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_THREAD_POOL_INTERFACE_H_
 #define BASE_TASK_SCHEDULER_SCHEDULER_THREAD_POOL_INTERFACE_H_
 
 #include <memory>
 
 #include "base/base_export.h"
 #include "base/memory/ref_counted.h"
 #include "base/task_scheduler/sequence.h"
 #include "base/task_scheduler/task.h"
 
 namespace base {
 namespace internal {
 
+class SchedulerWorkerThread;
+
 // Interface for a thread pool.
 class BASE_EXPORT SchedulerThreadPoolInterface {
  public:
   virtual ~SchedulerThreadPoolInterface() = default;
 
-  // Posts |task| to be executed by this thread pool as part of |sequence|. The
-  // scheduler's TaskTracker must have allowed |task| to be posted before this
-  // is called. This must only be called after |task|'s delayed run time.
-  virtual void PostTaskWithSequenceNow(std::unique_ptr<Task> task,
-                                       scoped_refptr<Sequence> sequence) = 0;
+  // Posts |task| to be executed as part of |sequence|. |task| will run on
+  // |worker_thread| if specified; otherwise it can run on a any thread owned by
+  // this pool. The scheduler's TaskTracker must have allowed |task| to be
+  // posted before this is called. This must only be called after |task|'s
+  // delayed run time.
+  virtual void PostTaskWithSequenceNow(
+      std::unique_ptr<Task> task,
+      scoped_refptr<Sequence> sequence,
+      SchedulerWorkerThread* worker_thread) = 0;
 };
 
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_TASK_SCHEDULER_SCHEDULER_THREAD_POOL_INTERFACE_H_