Don't crash when receiving a NULL policy file.

BUG=None
TEST=syscall_filter_unittest

Change-Id: Id9d38ddb2a01014a7bd97f9cce6d4fdc0cf878dd
Reviewed-on: https://gerrit.chromium.org/gerrit/28621
Tested-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: Elly Jones <ellyjones@chromium.org>
Commit-Ready: Jorge Lucangeli Obes <jorgelo@chromium.org>
2 files changed