GitLab

The USS implementation of bookmark sync launched with M77 and most code
has already been cleaned up.

Transaction versions embedded in BookmarkModel are no longer used and
can also be deleted.

Change-Id: Icfe2ab727edce293c73b7b3ae521df66a71d843a
Bug: 933756
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2081426Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#746457}