Fix platform_viewport_x11 so that window is initially shown

mojo/services/native_viewport/public/interfaces/native_viewport.mojom

Index: mojo/services/native_viewport/public/interfaces/native_viewport.mojom
diff --git a/mojo/services/native_viewport/public/interfaces/native_viewport.mojom b/mojo/services/native_viewport/public/interfaces/native_viewport.mojom
index ab1506e6f923026c2d75aa911e54191e2b2d0fb0..40036c65eb722d4315d29bbfab6901522977a871 100644
--- a/mojo/services/native_viewport/public/interfaces/native_viewport.mojom
+++ b/mojo/services/native_viewport/public/interfaces/native_viewport.mojom
@@ -26,6 +26,7 @@ struct SurfaceConfiguration {
 interface NativeViewport {
   // TODO(sky): having a create function is awkward. Should there be a factory
   // to create the NativeViewport that takes the size?
+  // When the viewport is created it is initially shown.
   Create(Size size, SurfaceConfiguration? requested_configuration) => (ViewportMetrics metrics);
 
   Show();