Allow FilePathWatcher to be used from sequenced tasks.

base/files/file_path_watcher_kqueue.h

 // Copyright 2014 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_FILES_FILE_PATH_WATCHER_KQUEUE_H_
 #define BASE_FILES_FILE_PATH_WATCHER_KQUEUE_H_
 
 #include <sys/event.h>
 
 #include <memory>
 #include <vector>
 
 #include "base/files/file_descriptor_watcher_posix.h"
 #include "base/files/file_path.h"
 #include "base/files/file_path_watcher.h"
 #include "base/macros.h"
-#include "base/single_thread_task_runner.h"
 
 namespace base {
 
 // Mac-specific file watcher implementation based on kqueue.
 // The Linux and Windows versions are able to detect:
 // - file creation/deletion/modification in a watched directory
 // - file creation/deletion/modification for a watched file
 // - modifications to the paths to a watched object that would affect the
 //   object such as renaming/attibute changes etc.
 // The kqueue implementation will handle all of the items in the list above
@@ skipping 91 matching lines @@
   // Throughout the lifetime of this, OnKQueueReadable() will be called when
   // data is available in |kqueue_|.
   std::unique_ptr<FileDescriptorWatcher::Controller> kqueue_watch_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(FilePathWatcherKQueue);
 };
 
 }  // namespace base
 
 #endif  // BASE_FILES_FILE_PATH_WATCHER_KQUEUE_H_