[gnome-shell] shell-app: Ignore invalid window PIDs

[Florian Müllner <fmuellner src gnome org>]

commit d4db5a59c1f4b9178bd793c6af0bd90f4df07610
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Mon Apr 6 20:31:46 2020 +0200

    shell-app: Ignore invalid window PIDs
    
    When building the list of window PIDs, it's possible Mutter doesn't know
    about the PID the client has and meta_window_get_pid() will return 0. We
    should handle this case by not adding the PID to the list of PIDs
    instead of adding an invalid one to it.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1184

 src/shell-app.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/src/shell-app.c b/src/shell-app.c
index dfa7fe7570..f72cba15d2 100644
--- a/src/shell-app.c
+++ b/src/shell-app.c
@@ -1159,6 +1159,10 @@ shell_app_get_pids (ShellApp *app)
     {
       MetaWindow *window = iter->data;
       int pid = meta_window_get_pid (window);
+
+      if (pid < 1)
+        continue;
+
       /* Note in the (by far) common case, app will only have one pid, so
        * we'll hit the first element, so don't worry about O(N^2) here.
        */