Fix misaligned overflow menu

+ Move PopupWindow down 8dp if overflow menu is anchored at bottom

BUG=735252

Change-Id: Ic0942d979f9c686d49f8ce3e264e0d0c88cced79
Reviewed-on: https://chromium-review.googlesource.com/563956
Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Becky Zhou <huayinz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487249}
1 file changed