Files: Add basic implementation of Directory and some basic tests.

services/files/shared_impl.h

+// 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.
+
+// Shared implementation of things common between |DirectoryImpl| and
+// |FileImpl|.
+
+#ifndef SERVICES_FILES_SHARED_IMPL_H_
+#define SERVICES_FILES_SHARED_IMPL_H_
+
+#include "mojo/public/cpp/bindings/callback.h"
+#include "services/files/types.mojom.h"
+
+namespace mojo {
+namespace files {
+
+// Stats the given FD (which must be valid), calling |callback| appropriately.
+void StatFD(int fd, const Callback<void(Error, FileInformationPtr)>& callback);
+
+// Touches the given FD (which must be valid), calling |callback| appropriately.
+void TouchFD(int fd,
+             TimespecOrNowPtr atime,
+             TimespecOrNowPtr mtime,
+             const Callback<void(Error)>& callback);
+
+}  // namespace files
+}  // namespace mojo
+
+#endif  // SERVICES_FILES_SHARED_IMPL_H_