mojo leveldb: Remove the created file thread.

components/filesystem/public/interfaces/file.mojom

 // Copyright 2015 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.
 
 // TODO(vtl): notes to self:
 //  - file offsets, file positions, and file sizes are int64 (though positions
 //    and sizes must always be non-negative)
 //  - buffer size parameters (for read/write) are uint32
 
 module filesystem;
@@ skipping 47 matching lines @@
   // I.e., the access mode, etc. (as specified to |Directory::OpenFile()| by the
   // |open_flags| argument) as well as file position.
   Dup(File& file) => (FileError error);
 
   // Syncs data to disk.
   Flush() => (FileError error);
 
   // Attempts to take an exclusive write lock on the file. This both takes a
   // native OS file lock (so that non-chrome, non-mojo processes can't write to
   // this file).
+  [Sync]
   Lock() => (FileError error);
 
   // Unlocks a previously locked file.
+  [Sync]
   Unlock() => (FileError error);
 
   // Returns a handle to the file for raw access.
   AsHandle() => (FileError error, handle file_handle);
 };