Support FileDescriptorWatcher in TaskScheduler.

base/task_scheduler/task_tracker_posix.cc

Index: base/task_scheduler/task_tracker_posix.cc
diff --git a/base/task_scheduler/task_tracker_posix.cc b/base/task_scheduler/task_tracker_posix.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5c54f371949acf6100eda4f0d8a301057402d4e5
--- /dev/null
+++ b/base/task_scheduler/task_tracker_posix.cc
@@ -0,0 +1,30 @@
+// 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_tracker_posix.h"
+
+#include <utility>
+
+#include "base/files/file_descriptor_watcher_posix.h"
+#include "base/logging.h"
+
+namespace base {
+namespace internal {
+
+TaskTrackerPosix::TaskTrackerPosix(
+    MessageLoopForIO* watch_file_descriptor_message_loop)
+    : watch_file_descriptor_message_loop_(watch_file_descriptor_message_loop) {
+  DCHECK(watch_file_descriptor_message_loop_);
+}
+
+TaskTrackerPosix::~TaskTrackerPosix() = default;
+
+void TaskTrackerPosix::PerformRunTask(std::unique_ptr<Task> task) {
+  FileDescriptorWatcher file_descriptor_watcher(
+      watch_file_descriptor_message_loop_);
+  TaskTracker::PerformRunTask(std::move(task));
+}
+
+}  // namespace internal
+}  // namespace base