chatdialog: Fix issue of creating QObjects in different thread.

Change-Id: I2f0dc2006cc330cd9d4fc5973eb475d841103b59
diff --git a/src/digesttreescene.cpp b/src/digesttreescene.cpp
index c2aa865..d692d4e 100644
--- a/src/digesttreescene.cpp
+++ b/src/digesttreescene.cpp
@@ -25,8 +25,10 @@
 
 //DisplayUserPtr DisplayUserNullPtr;
 
-DigestTreeScene::DigestTreeScene(QWidget *parent)
+DigestTreeScene::DigestTreeScene(ndn::shared_ptr<boost::asio::io_service> ioService,
+                                 QWidget *parent)
   : QGraphicsScene(parent)
+  , m_scheduler(*ioService)
 {
   previouslyUpdatedUser = DisplayUserNullPtr;
 }
@@ -58,7 +60,7 @@
   if (rePlot) 
   {
     plot(digest);
-    QTimer::singleShot(2100, this, SLOT(emitReplot()));
+    m_scheduler.scheduleEvent(ndn::time::milliseconds(600), ndn::bind(&DigestTreeScene::emitReplot, this));
   }
   else 
   {