Remove uses of LASTCHANGE in chrome_cleaner.

R=proberge

Bug: 913585
Change-Id: I42297b168d776767c56c83442df6eb3bed222e88
Reviewed-on: https://chromium-review.googlesource.com/c/1370401
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Joe Mason <joenotcharles@google.com>
Cr-Commit-Position: refs/heads/master@{#615261}
7 files changed