[mutter] backend/x11: Add API to get the X11 screen

[Marge Bot <marge-bot src gnome org>]

commit b1fb8cbf572e99190f2adac1c05eca7d71338add
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Sep 17 21:26:55 2021 +0200

    backend/x11: Add API to get the X11 screen
    
    Will be used to replace a similar ClutterX11 API.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2014>

 src/backends/x11/meta-backend-x11.c | 10 ++++++++++
 src/backends/x11/meta-backend-x11.h |  2 ++
 2 files changed, 12 insertions(+)
---
diff --git a/src/backends/x11/meta-backend-x11.c b/src/backends/x11/meta-backend-x11.c
index ccf6d92530..d2bbab45e7 100644
--- a/src/backends/x11/meta-backend-x11.c
+++ b/src/backends/x11/meta-backend-x11.c
@@ -61,6 +61,7 @@ struct _MetaBackendX11Private
 {
   /* The host X11 display */
   Display *xdisplay;
+  Screen *xscreen;
   xcb_connection_t *xcb;
   GSource *source;
   Window root_window;
@@ -868,6 +869,7 @@ meta_backend_x11_initable_init (GInitable    *initable,
     }
 
   priv->xdisplay = xdisplay;
+  priv->xscreen = DefaultScreenOfDisplay (xdisplay);
   priv->xcb = XGetXCBConnection (priv->xdisplay);
   priv->root_window = DefaultRootWindow (xdisplay);
 
@@ -955,6 +957,14 @@ meta_backend_x11_get_xdisplay (MetaBackendX11 *x11)
   return priv->xdisplay;
 }
 
+Screen *
+meta_backend_x11_get_xscreen (MetaBackendX11 *x11)
+{
+  MetaBackendX11Private *priv = meta_backend_x11_get_instance_private (x11);
+
+  return priv->xscreen;
+}
+
 Window
 meta_backend_x11_get_root_xwindow (MetaBackendX11 *backend_x11)
 {
diff --git a/src/backends/x11/meta-backend-x11.h b/src/backends/x11/meta-backend-x11.h
index eb15ba01c9..515cde91b4 100644
--- a/src/backends/x11/meta-backend-x11.h
+++ b/src/backends/x11/meta-backend-x11.h
@@ -49,6 +49,8 @@ struct _MetaBackendX11Class
 
 Display * meta_backend_x11_get_xdisplay (MetaBackendX11 *backend);
 
+Screen * meta_backend_x11_get_xscreen (MetaBackendX11 *backend);
+
 Window meta_backend_x11_get_root_xwindow (MetaBackendX11 *backend_x11);
 
 Window meta_backend_x11_get_xwindow (MetaBackendX11 *backend);