Refactor the io resource classes

runtime/observatory/tests/service/tcp_socket_service_test.dart

 // Copyright (c) 2015, 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.
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io' as io;
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
@@ skipping 47 matching lines @@
     expect(listening['id'], equals(result['data'][0]['id']));
     expect(listening['listening'], isTrue);
     expect(listening['socket_type'], equals('TCP'));
     expect(listening['port'], greaterThanOrEqualTo(1024));
     expectTimeBiggerThanZero(listening['last_read']);
 
     expect(listening['total_read'], equals(2));
     expect(listening['last_write'], equals(0));
     expect(listening['total_written'], equals(0));
     expect(listening['write_count'], equals(0));
-    expect(listening['read_count'], equals(0));
+    expect(listening['read_count'], equals(2));
     expect(listening['remote_host'], equals('NA'));
     expect(listening['remote_port'], equals('NA'));
 
     var client = await isolate.invokeRpcNoUpgrade(
         '__getSocketByID', { 'id' : result['data'][1]['id'] });
     expect(client['id'], equals(result['data'][1]['id']));
 
     var server = await isolate.invokeRpcNoUpgrade(
         '__getSocketByID', { 'id' : result['data'][2]['id'] });
     expect(server['id'], equals(result['data'][2]['id']));
@@ skipping 87 matching lines @@
     // Stopwatch resolution on windows make us sometimes report the same value.
     if (io.Platform.isWindows) {
       expect(server['last_read'], greaterThanOrEqualTo(client['last_write']));
     } else {
       expect(server['last_read'], greaterThan(client['last_write']));
     }
   },
 ];
 
 main(args) async => runIsolateTests(args, tcpTests, testeeBefore:setupTCP);