eclass-overlay: add user and group for image-burner

This is the first step to sandbox image-burner process.

Take a UID/GID that ranges from 300-399 from ./display-accts.py --show-free as I assume image-burner needs to talk to filesystems.

BUG=chromium:766130
TEST=Build image with updated chromeos-base/chromeos-imageburner, check
image-burner is in /etc/passwd and /etc/group.

Change-Id: I05cdf5f0385c7757652a64bbecceb85cb7a4e408
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/eclass-overlay/+/2823058
Reviewed-by: Allen Webb <allenwebb@google.com>
Tested-by: Zi Lin <lziest@chromium.org>
Commit-Queue: Allen Webb <allenwebb@google.com>
2 files changed
tree: 934ede109705fd8be7a7f945c0e52e0212720253
  1. OWNERS
  2. PRESUBMIT.cfg
  3. acct-group/
  4. acct-user/
  5. eclass/
  6. metadata/
  7. profiles/