[Gallery] Fix directory structure (#312)

gallery/tool/l10n_cli/main.dart

@@ -0,0 +1,17 @@
+// Copyright 2019 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:args/args.dart';
+
+import 'l10n_cli.dart' as l10n_cli;
+
+void main(List<String> arguments) {
+  final parser = ArgParser()
+    ..addFlag(
+      'dry-run',
+      help: 'Write the output to stdout.',
+    );
+  final argResults = parser.parse(arguments);
+  l10n_cli.englishArbsToXmls(isDryRun: argResults['dry-run'] as bool);
+}