Demonstrate external-window-mode in mus-demo

services/ui/display/platform_screen_ozone.cc

Index: services/ui/display/platform_screen_ozone.cc
diff --git a/services/ui/display/platform_screen_ozone.cc b/services/ui/display/platform_screen_ozone.cc
index 3a9433d18359257a14f0e81140c148a1920dd9c7..856064fe18de702c961552a37602b1ea273bdea9 100644
--- a/services/ui/display/platform_screen_ozone.cc
+++ b/services/ui/display/platform_screen_ozone.cc
@@ -18,6 +18,7 @@
 #include "ui/display/types/native_display_delegate.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/ozone/public/ozone_platform.h"
+#include "ui/ozone/public/ozone_switches.h"
 
 namespace display {
 namespace {
@@ -82,6 +83,10 @@ void PlatformScreenOzone::Init(PlatformScreenDelegate* delegate) {
         native_display_delegate->GetFakeDisplayController();
   }
 
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kExternalWindowMode))
+    return;
+
   // We want display configuration to happen even off device to keep the control
   // flow similar.
   display_configurator_.set_configure_display(true);