The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/246d898524d590d3116d492696678323112cb7b7

commit 246d898524d590d3116d492696678323112cb7b7
Author: Gauthier Ambard <gambard@chromium.org>
Date: Tue Jun 19 09:46:31 2018

Use frame instead of autolayout for popup shadow

This CL uses frames and autoresizing masks for positioning the popup
menu shadow instead of auto layout as auto layout is introducing a bug
on iPhone X where the shadow is 1px off.

Bug:  850519 
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Ia01d6abe924b5229b69676fe37ef251e11b60d31
Reviewed-on: https://chromium-review.googlesource.com/1104686
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568381}
[modify] https://crrev.com/246d898524d590d3116d492696678323112cb7b7/ios/chrome/browser/ui/popup_menu/popup_menu_view_controller.mm

The NextAction date has arrived: 2018-06-20

Background shadow is correctly aligned with the menu.
Verified on iPhone with Regular and Incognito modes.
Verified on M69.0.3473.0 canary
iOS: 11.4, 12

https://drive.google.com/file/d/1Iw0jhxXI_RH9oxnvI7BplCZREzZERnrX/view

For the record, this seems to have been a @3x-only issue.