check_ethernet.hook: stop honoring shill-start.lock

All users should have migrated to using
/run/autotest_pause_ethernet_hook, which is a more useful superset of
this lock. Some are using both (for now), but that still means we can
just honor one of them.

BUG=chromium:1018463
TEST=none

Cq-Depend: chromium:1884696
Change-Id: Iaa609485345dc21ea7c4294fb55bd545d90dd3a9
Reviewed-on: https://chromium-review.googlesource.com/1884697
Tested-by: Brian Norris <briannorris@chromium.org>
Commit-Ready: Brian Norris <briannorris@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Grant Grundler <grundler@chromium.org>
Reviewed-by: Matthew Wang <matthewmwang@chromium.org>
diff --git a/recover_duts/hooks/check_ethernet.hook b/recover_duts/hooks/check_ethernet.hook
index b36edbe..f5758b9 100755
--- a/recover_duts/hooks/check_ethernet.hook
+++ b/recover_duts/hooks/check_ethernet.hook
@@ -7,7 +7,6 @@
 
 set -e
 
-SHILL_START_LOCK_PATH="/run/lock/shill-start.lock"
 WIFI_CRED=/usr/local/etc/wifi_cred
 
 # See do_suspend() in src/third_party/autotest/files/client/cros/power/sys_power.py
@@ -209,14 +208,6 @@
 }
 
 restart_connection_manager() {
-  # NB: -e will fail on a dangling symlink. That's deliberate. The
-  # symlink should point at /proc/<locker's PID>. And if that path is
-  # gone, the locker has exited, and the lock is stale.
-  if [ -e "${SHILL_START_LOCK_PATH}" ]; then
-    lock_holder=$(readlink "${SHILL_START_LOCK_PATH}")
-    info_msg "Ignoring restart request; lock held by ${lock_holder}"
-    return
-  fi
   initctl stop shill || info_msg "Shill was not running."
   initctl start shill
 }