Remove FilePathWatcher::PlatformDelegate::CancelOnMessageLoopThread().

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 <vector>
 
@@ skipping 43 matching lines @@
    public:
     EventData(const FilePath& path, const FilePath::StringType& subdir)
         : path_(path), subdir_(subdir) { }
     FilePath path_;  // Full path to this item.
     FilePath::StringType subdir_;  // Path to any sub item.
   };
 
   typedef std::vector<struct kevent> EventVector;
 
   // Can only be called on |io_task_runner_|'s thread.
-  void CancelOnMessageLoopThread() override;
+  void CancelOnMessageLoopThread();
 
   // Returns true if the kevent values are error free.
   bool AreKeventValuesValid(struct kevent* kevents, int count);
 
   // Respond to a change of attributes of the path component represented by
   // |event|. Sets |target_file_affected| to true if |target_| is affected.
   // Sets |update_watches| to true if |events_| need to be updated.
   void HandleAttributesChange(const EventVector::iterator& event,
                               bool* target_file_affected,
                               bool* update_watches);
@@ skipping 49 matching lines @@
   FilePathWatcher::Callback callback_;
   FilePath target_;
   int kqueue_;
 
   DISALLOW_COPY_AND_ASSIGN(FilePathWatcherKQueue);
 };
 
 }  // namespace base
 
 #endif  // BASE_FILES_FILE_PATH_WATCHER_KQUEUE_H_