clean up modernize_visual_update_smaller_margins

Most code are cleaned up in https://crrev.com/c/5117866, here is the
only thing left.

Change-Id: Ib176f745d055dcc063d07ce722845efbb982168e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5415599


Commit-Queue: Gang Wu <gangwu@chromium.org>
Reviewed-by: Tomasz Wiszkowski <ender@google.com>
Cr-Commit-Position: refs/heads/main@{#1281831}