Complete the switch to ServiceObject

runtime/bin/vmservice/client/lib/src/elements/message_viewer.dart

-// Copyright (c) 2013, 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 message_viewer_element;
-
-import 'package:logging/logging.dart';
-import 'package:observatory/app.dart';
-import 'package:polymer/polymer.dart';
-import 'observatory_element.dart';
-
-@CustomTag('message-viewer')
-class MessageViewerElement extends ObservatoryElement {
-  Map _message;
-  @published Map get message => _message;
-  @published ObservatoryApplication app;
-
-  @published set message(Map m) {
-    if (m == null) {
-      Logger.root.info('Viewing null message.');
-      return;
-    }
-    Logger.root.info('Viewing message of type \'${m['type']}\'');
-    _message = m;
-    notifyPropertyChange(#messageType, "", messageType);
-  }
-
-  MessageViewerElement.created() : super.created();
-
-  String get messageType {
-    if (message == null || message['type'] == null) {
-      return 'Error';
-    }
-    return message['type'];
-  }
-}