Do not JSON encode the 'result' of a service rpc.

runtime/observatory/lib/src/app/application.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.
 
 part of app;
 
 /// The observatory application. Instances of this are created and owned
 /// by the observatory_application custom element.
 class ObservatoryApplication extends Observable {
   static ObservatoryApplication app;
   final _pageRegistry = new List<Page>();
   @observable Page currentPage;
   @observable final LocationManager locationManager;
   VM _vm;
   VM get vm => _vm;
   set vm(VM vm) {
     if (_vm == vm) {
       // Do nothing.
       return;
     }
     if (_vm != null) {
       // Disconnect from current VM.
       notifications.clear();
       _vm.disconnect();
     }
     if (vm != null) {
       Logger.root.info('Registering new VM callbacks');
-      vm.onConnect.then(_vmConnected);
-      vm.onDisconnect.then(_vmDisconnected);
+
+      vm.onConnect.then((_) {
+        if (vm is WebSocketVM) {
+          targets.add(vm.target);
+        }
+        _removeDisconnectEvents();
+      });
+
+      vm.onDisconnect.then((String reason) {
+        if (this.vm != vm) {
+          // This disconnect event occured *after* a new VM was installed.
+          return;
+        }
+        notifications.add(new ServiceEvent.connectionClosed(reason));
+      });
+
       vm.errors.stream.listen(_onError);
       vm.events.stream.listen(_onEvent);
       vm.exceptions.stream.listen(_onException);
     }
     _vm = vm;
   }
   final TargetManager targets;
   @reflectable final ObservatoryApplicationElement rootElement;
 
   TraceViewElement _traceView = null;
@@ skipping 157 matching lines @@
 
   ObservatoryApplication(this.rootElement) :
       locationManager = new HashLocationManager(),
       targets = new TargetManager() {
     vm = new WebSocketVM(targets.defaultTarget);
     _initOnce(false);
   }
 
   void _removeDisconnectEvents() {
     notifications.removeWhere((oldEvent) {
-        return (oldEvent.eventType == ServiceEvent.kVMDisconnected);
+        return (oldEvent.eventType == ServiceEvent.kConnectionClosed);
       });
   }
-
-  _vmConnected(VM vm) {
-    if (vm is WebSocketVM) {
-      targets.add(vm.target);
-    }
-    _removeDisconnectEvents();
-  }
-
-  _vmDisconnected(VM vm) {
-    if (this.vm != vm) {
-      // This disconnect event occured *after* a new VM was installed.
-      return;
-    }
-    this.vm = null;
-    notifications.add(new ServiceEvent.vmDisconencted());
-  }
 }