Roll Observatory packages and add a roll script

usage/lib/src/usage_impl_io.dart

-// Copyright (c) 2014, 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 usage_impl_io;
-
-import 'dart:async';
-import 'dart:convert' show JSON;
-import 'dart:io';
-
-import 'package:path/path.dart' as path;
-
-import 'usage_impl.dart';
-
-String _createUserAgent() {
-  // Mozilla/5.0 (iPhone; U; CPU iPhone OS 5_1_1 like Mac OS X; en)
-  // Dart/1.8.0-edge.41170 (macos; macos; macos; null)
-  String os = Platform.operatingSystem;
-  String locale = Platform.environment['LANG'];
-  return "Dart/${_dartVersion()} (${os}; ${os}; ${os}; ${locale})";
-}
-
-String _userHomeDir() {
-  String envKey = Platform.operatingSystem == 'windows' ? 'APPDATA' : 'HOME';
-  String value = Platform.environment[envKey];
-  return value == null ? '.' : value;
-}
-
-String _dartVersion() {
-  String ver = Platform.version;
-  int index = ver.indexOf(' ');
-  if (index != -1) ver = ver.substring(0, index);
-  return ver;
-}
-
-class IOPostHandler extends PostHandler {
-  final String _userAgent;
-  final HttpClient mockClient;
-
-  IOPostHandler({HttpClient this.mockClient}) : _userAgent = _createUserAgent();
-
-  Future sendPost(String url, Map<String, String> parameters) {
-    // Add custom parameters for OS and the Dart version.
-    parameters['cd1'] = Platform.operatingSystem;
-    parameters['cd2'] = 'dart ${_dartVersion()}';
-
-    String data = postEncode(parameters);
-
-    HttpClient client = mockClient != null ? mockClient : new HttpClient();
-    client.userAgent = _userAgent;
-    return client.postUrl(Uri.parse(url)).then((HttpClientRequest req) {
-      req.write(data);
-      return req.close();
-    }).then((HttpClientResponse response) {
-      response.drain();
-    }).catchError((e) {
-      // Catch errors that can happen during a request, but that we can't do
-      // anything about, e.g. a missing internet conenction.
-    });
-  }
-}
-
-class IOPersistentProperties extends PersistentProperties {
-  File _file;
-  Map _map;
-
-  IOPersistentProperties(String name) : super(name) {
-    String fileName = '.${name.replaceAll(' ', '_')}';
-    _file = new File(path.join(_userHomeDir(), fileName));
-    _file.createSync();
-    String contents = _file.readAsStringSync();
-    if (contents.isEmpty) contents = '{}';
-    _map = JSON.decode(contents);
-  }
-
-  dynamic operator[](String key) => _map[key];
-
-  void operator[]=(String key, dynamic value) {
-    if (value == null) {
-      _map.remove(key);
-    } else {
-      _map[key] = value;
-    }
-
-    _file.writeAsStringSync(JSON.encode(_map) + '\n');
-  }
-}