GitLab

The removed code was originally used to make shelf remain transparent
for fullscreen backdrop window [1]. Now the shelf is no longer
transparent, it should be removed.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/606706

Bug: b/79201599
Change-Id: Ic5b214cc714a7699d8ea4fda1a059a7d03104f6c
Reviewed-on: https://chromium-review.googlesource.com/1224640Reviewed-by: Robert Flack <flackr@chromium.org>
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#591403}