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

runtime/observatory/lib/src/app/application.dart

Index: runtime/observatory/lib/src/app/application.dart
diff --git a/runtime/observatory/lib/src/app/application.dart b/runtime/observatory/lib/src/app/application.dart
index d87d6fb6339416b0ed32c2fe8d92ee40876a3f16..fbe49a8cdbe4dfc919c63ee9c6c95fe126bb9f65 100644
--- a/runtime/observatory/lib/src/app/application.dart
+++ b/runtime/observatory/lib/src/app/application.dart
@@ -25,8 +25,22 @@ class ObservatoryApplication extends Observable {
     }
     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);
@@ -204,23 +218,7 @@ class ObservatoryApplication extends Observable {
 
   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());
-  }
 }