Camera: use an empty app id for host apps

Sending an app id that doesn't resolve to valid app info (e.g. a desktop
file is not found) will automatically reject camera request, because the
backend is not able to verify whether the app (based on app id) runs in
the background. Same will happen if the app id resolves to an app where
our app was started from. This happens for example when you start apps
in GNOME using Alt + F2, where we get invalid app id from cgroups and
since it doesn't find opened application window for this app, it will
automatically reject the request. Using an empty id fixes this problem.

(cherry picked from commit 6cd99b0)

Author: grulja

src/camera.c

@@ -76,7 +76,10 @@ handle_access_camera_in_thread_func (GTask *task,
   const char *app_id;
   gboolean allowed;
 
-  app_id = (const char *)g_object_get_data (G_OBJECT (request), "app-id");
+  if (xdp_app_info_is_host (request->app_info))
+    app_id = "";
+  else
+    app_id = (const char *)g_object_get_data (G_OBJECT (request), "app-id");
 
   allowed = device_query_permission_sync (app_id, "camera", request);