Support FileDescriptorWatcher in TaskScheduler.

base/task_scheduler/task_tracker_posix.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_TRACKER_POSIX_H_
+#define BASE_TASK_SCHEDULER_TASK_TRACKER_POSIX_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "base/task_scheduler/task_tracker.h"
+
+namespace base {
+
+class MessageLoopForIO;
+
+namespace internal {
+
+struct Task;
+
+// A TaskTracker that performs POSIX-specific work before running a task.
+class BASE_EXPORT TaskTrackerPosix : public TaskTracker {

[robliao, 2016/10/20 00:59:40]

Is a BASE_EXPORT currently required for TaskTrackerPosix?

[fdoray, 2016/10/21 12:29:43]

Done.

+ public:
+  // |watch_file_descriptor_message_loop| is used to setup FileDescriptorWatcher
+  // in the scope in which a Task runs.
+  TaskTrackerPosix(MessageLoopForIO* watch_file_descriptor_message_loop);
+

[robliao, 2016/10/20 00:59:40]

Nit: No line break needed here.

[fdoray, 2016/10/21 12:29:43]

Done.

+  ~TaskTrackerPosix();
+
+ private:
+  // TaskTracker:
+  void PerformRunTask(std::unique_ptr<Task> task) override;
+
+  MessageLoopForIO* const watch_file_descriptor_message_loop_;
+
+  DISALLOW_COPY_AND_ASSIGN(TaskTrackerPosix);
+};
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_TASK_SCHEDULER_TASK_TRACKER_POSIX_H_