Commit Martin's patch for pub + lib_v2.

utils/pub/validator/directory.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library directory_validator;
 
+import 'dart:async';
+
 import '../entrypoint.dart';
 import '../io.dart';
 import '../validator.dart';
 
 /// A validator that validates a package's top-level directories.
 class DirectoryValidator extends Validator {
   DirectoryValidator(Entrypoint entrypoint)
     : super(entrypoint);
 
   static final _PLURAL_NAMES = ["tools", "tests", "docs", "examples"];
 
   Future validate() {
-    return listDir(entrypoint.root.dir).chain((dirs) {
+    return listDir(entrypoint.root.dir).then((dirs) {
       return Futures.wait(dirs.mappedBy((dir) {
         return dirExists(dir).then((exists) {
           if (!exists) return;
 
           dir = basename(dir);
           if (_PLURAL_NAMES.contains(dir)) {
             // Cut off the "s"
             var singularName = dir.substring(0, dir.length - 1);
             warnings.add('Rename the top-level "$dir" directory to '
                     '"$singularName".\n'
                 'The Pub layout convention is to use singular directory '
                     'names.\n'
                 'Plural names won\'t be correctly identified by Pub and other '
                     'tools.');
           }
 
           if (dir.contains(new RegExp(r"^samples?$"))) {
             warnings.add('Rename the top-level "$dir" directory to "example".\n'
                 'This allows Pub to find your examples and create "packages" '
                     'directories for them.\n');
           }
         });
       }));
     });
   }
 }