GitLab

Document that the rollback feature relies on install attributes to be
backwards compatible.

Bug: 1124428
Change-Id: I0a9de16aa5bd749300a05751562fe7c6436c9e38
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2435192Reviewed-by: Sergey Poromov <poromov@chromium.org>
Commit-Queue: Miriam Polzer <mpolzer@google.com>
Cr-Commit-Position: refs/heads/master@{#812616}