Create new password-viewers group and add shill to it.

This new group will be used to gate access to the user's login
password that is saved in a kernel keyring.

BUG=chromium:812678
TEST=display_accts.py
CQ-DEPEND=CL:1142287

Change-Id: I8cbc819f3203eb99adf76aab704f1833c4027657
Reviewed-on: https://chromium-review.googlesource.com/1137231
Commit-Ready: May Lippert <maybelle@chromium.org>
Tested-by: May Lippert <maybelle@chromium.org>
Reviewed-by: Micah Morton <mortonm@chromium.org>
(cherry picked from commit 0aef252c0db32840aaac21451a8ea52dc3ecef7e)
Reviewed-on: https://chromium-review.googlesource.com/1156785
Reviewed-by: May Lippert <maybelle@chromium.org>
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Commit-Queue: May Lippert <maybelle@chromium.org>
diff --git a/profiles/base/accounts/group/password-viewers b/profiles/base/accounts/group/password-viewers
new file mode 100644
index 0000000..1f35cbf
--- /dev/null
+++ b/profiles/base/accounts/group/password-viewers
@@ -0,0 +1,5 @@
+# Members of this group will be able to read the user's login password saved in
+# a kernel keyring.
+group:password-viewers
+gid:611
+users:shill