It didn't work by itself. It was just a redundant information of
whether the scrollbar theme supports solid color scrollbars.

Change-Id: Ib5f59fbc30ef8ef83a2e0b9b36729214ca68ce2e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1894433
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712010}