Converted observatory flag-list element

runtime/observatory/lib/src/mocks/repositories/flag.dart

+// Copyright (c) 2016, 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
+
+part of mocks;
+
+typedef Future<Iterable<M.Flag>> FlagsRepositoryMockCallback(M.VMRef vm);
+
+class FlagsRepositoryMock implements M.FlagsRepository {
+  final FlagsRepositoryMockCallback _list;
+
+  Future<Iterable<M.Flag>> list(M.VMRef vm) {
+    if (_list != null) {
+      return _list(vm);
+    }
+    return new Future.value(const []);
+  }
+
+  FlagsRepositoryMock({FlagsRepositoryMockCallback list})
+    : _list = list;
+}