GitLab

Fixes menu positioning miscalculations in ShelfView,
also refactors GetMenuAnchorRect so its more readable.

Bug: 852153
Change-Id: Ie8c377de9b2191c3ae739f5adec7f16fc8003bd7
Reviewed-on: https://chromium-review.googlesource.com/1102028
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569816}