Add WindowPinType property on arua::Window

ash/public/cpp/mus_property_mirror_ash.cc

Index: ash/public/cpp/mus_property_mirror_ash.cc
diff --git a/ash/public/cpp/mus_property_mirror_ash.cc b/ash/public/cpp/mus_property_mirror_ash.cc
index 25ddc91fbe390511e6bfe7ebf109378addccc693..770c4a1ff6fc1540ccba1a2f4392daee835939df 100644
--- a/ash/public/cpp/mus_property_mirror_ash.cc
+++ b/ash/public/cpp/mus_property_mirror_ash.cc
@@ -37,6 +37,9 @@ void MusPropertyMirrorAsh::MirrorPropertyFromWidgetWindowToRootWindow(
   } else if (key == kShelfItemTypeKey) {
     int32_t value = window->GetProperty(kShelfItemTypeKey);
     root_window->SetProperty(kShelfItemTypeKey, value);
+  } else if (key == kWindowPinTypeKey) {
+    ash::mojom::WindowPinType value = window->GetProperty(kWindowPinTypeKey);
+    root_window->SetProperty(kWindowPinTypeKey, value);
   } else if (key == aura::client::kAppIconKey) {
     MirrorOwnedProperty(window, root_window, aura::client::kAppIconKey);
   } else if (key == aura::client::kAppIdKey) {