GitLab

Instead of displaying the PhoneHub UI in the middle of the screen
when shelf position is right/left, it is now displayed on the bottom.

Screenshots:
Left shelf - https://screenshot.googleplex.com/5LBcDUSEWY5vER6
Right shelf - https://screenshot.googleplex.com/4AboKZpVjH89tMS
Bottom shelf - https://screenshot.googleplex.com/iumxiW5ohmL9L7w

Fixed: 1159098
Bug: 1106937
Change-Id: Ie715e0f61b46bce469e5aa661e43ac46680d8138
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2600626Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Regan Hsu <hsuregan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#838947}