Xpra: Ticket #2753: guess content-type from parent pid

If we don't find a match for the window using the regular content-type guessing code (#1950), use the parent pid. Useful for applications like steam: all children processes should use video by default.

See Find parent pid given a pid: requires libproc-dev.

#include <proc/readproc.h>
void printppid(pid_t pid) {
    proc_t process_info;
    get_proc_stats(pid, &process_info);
    printf("Parent of pid=%d is pid=%d\n", pid, process_info.ppid);

Sun, 05 Jul 2020 09:56:16 GMT - Antoine Martin: status, milestone changed

Sat, 23 Jan 2021 05:59:50 GMT - migration script:

this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/2753