Add tools/ddbg_service.

runtime/bin/vmservice/observatory/lib/service_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 service_io;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:typed_data';
 
@@ skipping 11 matching lines @@
                void onError(),
                void onClose()) {
     WebSocket.connect(address).then((WebSocket socket) {
       _webSocket = socket;
       _webSocket.listen(
           onMessage,
           onError: (dynamic) => onError(),
           onDone: onClose,
           cancelOnError: true);
       onOpen();
+    }).catchError((e, st) {
+      onError();
     });
   }
   
   bool get isOpen =>
       (_webSocket != null) && (_webSocket.readyState == WebSocket.OPEN);
   
   void send(dynamic data) {
     _webSocket.add(data);
   }
   
   void close() {
-    _webSocket.close();
+    if (_webSocket != null) {
+      _webSocket.close();
+    }
   }
   
   Future<ByteData> nonStringToByteData(dynamic data) {
     assert(data is Uint8List);
     print('nonString: ${data.lengthInBytes}, $data');
     return new Future.sync(() =>
         new ByteData.view(data.buffer,
                           data.offsetInBytes,
                           data.lengthInBytes));
   }
 }
 
 /// The [WebSocketVM] communicates with a Dart VM over WebSocket. The Dart VM
 /// can be embedded in Chromium or standalone. In the case of Chromium, we
 /// make the service requests via the Chrome Remote Debugging Protocol.
 class WebSocketVM extends CommonWebSocketVM {
   WebSocketVM(WebSocketVMTarget target) : super(target, new _IOWebSocket());
 }