Revert of file_manager: Migrate FILE thread to TaskScheduler

chrome/browser/chromeos/file_manager/file_watcher.h

 // Copyright 2013 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 CHROME_BROWSER_CHROMEOS_FILE_MANAGER_FILE_WATCHER_H_
 #define CHROME_BROWSER_CHROMEOS_FILE_MANAGER_FILE_WATCHER_H_
 
 #include <map>
 #include <string>
 
 #include "base/callback_forward.h"
 #include "base/files/file_path.h"
 #include "base/files/file_path_watcher.h"
 #include "base/memory/weak_ptr.h"
-#include "base/sequenced_task_runner.h"
 
 namespace file_manager {
 
 // This class is used to watch changes in the given virtual path, remember
 // what extensions are watching the path.
 //
 // For local files, the class maintains a FilePathWatcher instance and
 // remembers what extensions are watching the path.
 //
 // For remote files (ex. files on Drive), the class just remembers what
@@ skipping 38 matching lines @@
       const base::FilePath& local_path,
       const base::FilePathWatcher::Callback& file_watcher_callback,
       const BoolCallback& callback);
 
  private:
   // Called when a FilePathWatcher is created and started.
   // |file_path_watcher| is NULL, if the watcher wasn't started successfully.
   void OnWatcherStarted(const BoolCallback& callback,
                         base::FilePathWatcher* file_path_watcher);
 
-  scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner_;
   base::FilePathWatcher* local_file_watcher_;
   base::FilePath virtual_path_;
   // Map of extension-id to counter. See the comment at AddExtension() for
   // why we need to count.
   typedef std::map<std::string, int> ExtensionCountMap;
   ExtensionCountMap extensions_;
 
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate the weak pointers before any other members are destroyed.
   base::WeakPtrFactory<FileWatcher> weak_ptr_factory_;
 };
 
 }  // namespace file_manager
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILE_MANAGER_FILE_WATCHER_H_