Add mojom module suffix in .mojom files for components/filesystem.

components/filesystem/public/interfaces/directory.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.
 
-module filesystem;
+module filesystem.mojom;
 
 import "components/filesystem/public/interfaces/file.mojom";
 import "components/filesystem/public/interfaces/types.mojom";
 
 struct FileOpenDetails {
   string path;
   uint32 open_flags;
 };
 
 struct FileOpenResult {
@@ skipping 81 matching lines @@
   WriteFile(string path, array<uint8> data) => (FileError error);
 
   // TODO(vtl): directory "streaming"?
   // TODO(vtl): "make root" (i.e., prevent cd-ing, etc., to parent); note that
   // this would require a much more complicated implementation (e.g., it needs
   // to be "inherited" by OpenDirectory(), and the enforcement needs to be valid
   // even if the opened directory is subsequently moved -- e.g., closer to the
   // "root")
   // TODO(vtl): Add a "watch"?
 };