The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform2/+/c2448fca8972fbb84e0204ae70544a3980b64d90

commit c2448fca8972fbb84e0204ae70544a3980b64d90
Author: C Shapiro <shapiroc@chromium.org>
Date: Tue Sep 11 00:17:49 2018

chromeos-config: Add fw updater script config

Support setting the updater script dynamically to support the migration
to updater5.sh

BUG= chromium:882413 
TEST=run_tests.sh

Change-Id: I0450462927eec5451951e9aaca53e60ccd4cb430
Reviewed-on: https://chromium-review.googlesource.com/1216162
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: C Shapiro <shapiroc@google.com>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>

[modify] https://crrev.com/c2448fca8972fbb84e0204ae70544a3980b64d90/chromeos-config/libcros_config/test_build.json
[modify] https://crrev.com/c2448fca8972fbb84e0204ae70544a3980b64d90/chromeos-config/libcros_config/test.yaml
[modify] https://crrev.com/c2448fca8972fbb84e0204ae70544a3980b64d90/chromeos-config/libcros_config/test_import.json
[modify] https://crrev.com/c2448fca8972fbb84e0204ae70544a3980b64d90/chromeos-config/cros_config_host/cros_config_schema.yaml
[modify] https://crrev.com/c2448fca8972fbb84e0204ae70544a3980b64d90/chromeos-config/cros_config_host/cros_config_schema.py
[modify] https://crrev.com/c2448fca8972fbb84e0204ae70544a3980b64d90/chromeos-config/cros_config_host/libcros_config_host_json.py
[modify] https://crrev.com/c2448fca8972fbb84e0204ae70544a3980b64d90/chromeos-config/libcros_config/test_merge.json

In the end we decided to only set script in ebuild files, not yaml config.