Re-add the on error callback to instance tasks

This patch sets the error callback for the instance
tasks created so that the instance manager reports
the error output via its introspec. This report
was present in precedent version. So this patch
re-introduce this behavior

Change-Id: Ic4393ab107e882a110714704dea4b78170f94b82
Closes-Bug: #1470122

src/vnsw/agent/oper/instance_manager.cc

@@ -278,7 +278,6 @@ void InstanceManager::OnErrorEventHandler(InstanceManagerChildEvent event) {
            UnregisterSvcInstance(event.task);
        }
     }
-    ScheduleNextTask(event.task_queue);
 }
 
 bool InstanceManager::DequeueEvent(InstanceManagerChildEvent event) {
@@ -576,6 +575,8 @@ void InstanceManager::StartServiceInstance(ServiceInstance *svc_instance,
     if (adapter != NULL) {
         InstanceTask *task = adapter->CreateStartTask(props, update);
         if (task != NULL) {
+            task->set_on_error_cb(boost::bind(&InstanceManager::OnError,
+                                              this, _1, _2));
             state->set_properties(props);
             RegisterSvcInstance(task, svc_instance);
             std::stringstream info;