login_manager: Fix X server VT-switching regression.
The XServerRunner code added by 9009cb84 left SIGUSR1
blocked in the forked process that it uses to exec the X
server. This broke X's VT-switching code (e.g. Ctrl-Alt-F2),
which interestingly depends on SIGUSR1 (see
kbdLinuxVTSignalHandler() in hw/dmx/input/lnx-keyboard.c).
Also simplify some ugly code in XServerRunner and add an
explanation of how it works to its header.
BUG=chromium:380713
TEST=manually checked that ctrl-alt-f2 works again in dev
mode and updated unit tests to check that no signals
are blocked
Change-Id: Ib8c0b0552b1d5421cdea51fe782f845698ade7ae
Reviewed-on: https://chromium-review.googlesource.com/202591
Tested-by: Daniel Erat <derat@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Daniel Erat <derat@chromium.org>
3 files changed
