Add an aura window property for Immersive fullscreen mode

ui/aura/mus/property_converter.cc

Index: ui/aura/mus/property_converter.cc
diff --git a/ui/aura/mus/property_converter.cc b/ui/aura/mus/property_converter.cc
index 47fe11b2a69d8f43fec2246b1a2ed3d69c9aabb9..98722967b671da378e289b3889f17f0a2dcff001 100644
--- a/ui/aura/mus/property_converter.cc
+++ b/ui/aura/mus/property_converter.cc
@@ -37,6 +37,8 @@ PropertyConverter::PropertyConverter() {
                    ui::mojom::WindowManager::kAppIcon_Property);
   RegisterProperty(client::kAppIdKey,
                    ui::mojom::WindowManager::kAppID_Property);
+  RegisterProperty(client::kImmersiveFullscreenKey,
+                   ui::mojom::WindowManager::kImmersiveFullscreen_Property);
   RegisterProperty(client::kNameKey, ui::mojom::WindowManager::kName_Property);
   RegisterProperty(client::kPreferredSize,
                    ui::mojom::WindowManager::kPreferredSize_Property);