controller: fix switching identity bug

Change-Id: If0c64b5a758f7a3531ed6cbf400cef03bed349a3
diff --git a/src/controller.cpp b/src/controller.cpp
index 1b585c1..a21a621 100644
--- a/src/controller.cpp
+++ b/src/controller.cpp
@@ -459,7 +459,7 @@
 {
   while (!m_chatDialogList.empty()) {
     ChatDialogList::const_iterator it = m_chatDialogList.begin();
-    onRemoveChatDialog(QString::fromStdString(it->first));
+    it->second->shutdown();
   }
 
   emit closeDBModule();