GitLab

Do not allow the drag if the drag position starts above the shelf.

Bug: 997885
Change-Id: Ifd5619cd28d96de889c28cd2c51fe67586224783
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1880079Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Xiaoqian Dai <xdai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709618}