[gtk: 1/5] gdk: Use application_id as xdg_shell's app_id if available

[Matthias Clasen <matthiasc src gnome org>]

commit 72ec8963d7df0e39f688838e42445c869e4875c9
Author: Guido Günther <agx sigxcpu org>
Date:   Thu Aug 2 11:03:41 2018 +0200

    gdk: Use application_id as xdg_shell's app_id if available
    
    This (manually) reverts commit e1fd87728dd841cf1d71025983107765e395b152
    
    This makes sure xdg_shell's app_id matches the DBus name of the the
    appliation when using GtkApplication. It also allows the compositor to
    derive the desktop file ID from the app_id:
    
       
https://cgit.freedesktop.org/wayland/wayland-protocols/tree/stable/xdg-shell/xdg-shell.xml?id=298d888ac718eae57ff2245d373d4327074506ea#n598
    
    Closes #653

 gdk/wayland/gdksurface-wayland.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/gdk/wayland/gdksurface-wayland.c b/gdk/wayland/gdksurface-wayland.c
index 51eca561df..af5881007d 100644
--- a/gdk/wayland/gdksurface-wayland.c
+++ b/gdk/wayland/gdksurface-wayland.c
@@ -1515,7 +1515,9 @@ gdk_wayland_surface_create_xdg_toplevel (GdkSurface *surface)
 
   impl->initial_fullscreen_output = NULL;
 
-  app_id = g_get_prgname ();
+  app_id = impl->application.application_id;
+  if (app_id == NULL)
+    app_id = g_get_prgname ();
 
   if (app_id == NULL)
     app_id = "GTK+ Application";