Move Task Scheduler Single Thread Task Runners to Dedicated Threads

base/task_scheduler/scheduler_single_thread_worker_pool_manager.h

Index: base/task_scheduler/scheduler_single_thread_worker_pool_manager.h
diff --git a/base/task_scheduler/scheduler_single_thread_worker_pool_manager.h b/base/task_scheduler/scheduler_single_thread_worker_pool_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..9d1b070a4c234595e70f80d50412c5bf230bf422
--- /dev/null
+++ b/base/task_scheduler/scheduler_single_thread_worker_pool_manager.h
@@ -0,0 +1,77 @@
+// Copyright 2017 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_SINGLE_THREAD_WORKER_POOL_MANAGER_H_
+#define BASE_TASK_SCHEDULER_SCHEDULER_SINGLE_THREAD_WORKER_POOL_MANAGER_H_
+
+#include <stddef.h>
+
+#include <memory>
+#include <vector>
+
+#include "base/base_export.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/single_thread_task_runner.h"
+#include "base/task_scheduler/scheduler_lock.h"
+#include "base/task_scheduler/scheduler_worker_pool_impl.h"
+#include "base/task_scheduler/task_scheduler.h"
+
+namespace base {
+
+class SchedulerWorkerPoolParams;
+class TaskTraits;
+
+namespace internal {
+
+class DelayedTaskManager;
+class TaskTracker;
+
+// Manages a pool of single-threaded worker pools mapped to one
+// SingleThreadTaskRunner.
+//
+// To maintain the same single thread threading environment for the trait
+// targeting a SchedulerWorkerPoolImpl, this also maintains the original
+// incoming SchedulerWorkerPoolParams and the WorkerPoolIndexForTraitsCallback
+// to create a single thread SchedulerWorkerPoolImpl of the exact same threading
+// environment.
+//
+// A single SingleThreadSchedulerWorkerPoolImplPool maintains a pool of
+// SchedulerWorkerPoolImpls of SchedulerWorkerPoolParams parameters. These are
+// held by |worker_pool_impl_pools_| and indexed the same way as
+// SchedulerWorkerPoolImpls in TaskSchedulerImpl.
+class BASE_EXPORT SchedulerSingleThreadWorkerPoolManager final {
+ public:
+  SchedulerSingleThreadWorkerPoolManager(
+      const std::vector<SchedulerWorkerPoolParams>& worker_pool_params_vector,
+      const TaskScheduler::WorkerPoolIndexForTraitsCallback&
+          worker_pool_index_for_traits_callback,
+      TaskTracker* task_tracker,
+      DelayedTaskManager* delayed_task_manager);
+  ~SchedulerSingleThreadWorkerPoolManager();
+
+  scoped_refptr<SingleThreadTaskRunner> CreateSingleThreadTaskRunnerWithTraits(
+      const TaskTraits& traits);
+
+  void JoinForTesting();
+  void WaitForAllWorkersIdleForTesting();
+
+ private:
+  class SingleThreadSchedulerWorkerPoolImplPool;
+
+  const TaskScheduler::WorkerPoolIndexForTraitsCallback
+      worker_pool_index_for_traits_callback_;
+
+  // Synchronizes access to |worker_pool_impl_pools_|.
+  SchedulerLock lock_;
+  std::vector<std::unique_ptr<SingleThreadSchedulerWorkerPoolImplPool>>
+      worker_pool_impl_pools_;
+
+  DISALLOW_COPY_AND_ASSIGN(SchedulerSingleThreadWorkerPoolManager);
+};
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_TASK_SCHEDULER_SCHEDULER_SINGLE_THREAD_WORKER_POOL_MANAGER_H_