Mus Demo: Extract code specific to internal mode into a separate class

services/ui/demo/main.cc

Index: services/ui/demo/main.cc
diff --git a/services/ui/demo/main.cc b/services/ui/demo/main.cc
index ecf56bd8398f53749ff9e6f58770784fb2b72150..20142861370e555eba103c3038c4af28c8b43136 100644
--- a/services/ui/demo/main.cc
+++ b/services/ui/demo/main.cc
@@ -4,9 +4,9 @@
 
 #include "services/service_manager/public/c/main.h"
 #include "services/service_manager/public/cpp/service_runner.h"
-#include "services/ui/demo/mus_demo.h"
+#include "services/ui/demo/mus_demo_internal.h"
 
 MojoResult ServiceMain(MojoHandle service_request_handle) {
-  service_manager::ServiceRunner runner(new ui::demo::MusDemo);
+  service_manager::ServiceRunner runner(new ui::demo::MusDemoInternal);
   return runner.Run(service_request_handle);
 }