GitLab

The update engine sends a flag for enterprise rollback.
Instead of guessing whether the current update is an enterprise
rollback using channels and versions, we use the rollback flag together
with the powerwash flag to determine which kind of update is happening.

Bug: 864672
Change-Id: Ia9a97b2bfe8abf5d795a2b530689321b9d585a0d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2215058Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Miriam Polzer <mpolzer@google.com>
Cr-Commit-Position: refs/heads/master@{#772579}