Create the desktop environment before any of the channel were connected.

remoting/host/client_session.h

Index: remoting/host/client_session.h
diff --git a/remoting/host/client_session.h b/remoting/host/client_session.h
index 778243db1a69c5dffd1089ac88a87108b8fdd4ea..add2a0a12313316de7f3bfa4679f8cab3e88c452 100644
--- a/remoting/host/client_session.h
+++ b/remoting/host/client_session.h
@@ -53,8 +53,9 @@ class ClientSession
   // Callback interface for passing events to the ChromotingHost.
   class EventHandler {
    public:
-    // Called after authentication has finished successfully.
-    virtual void OnSessionAuthenticated(ClientSession* client) = 0;
+    // Called after authentication has finished successfully. Returns true if
+    // the connection is allowed, or false otherwise.
+    virtual bool OnSessionAuthenticated(ClientSession* client) = 0;
 
     // Called after we've finished connecting all channels.
     virtual void OnSessionChannelsConnected(ClientSession* client) = 0;