The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2eab8d34fcdf23fb06fbd336f8ca38043d56d62f

commit 2eab8d34fcdf23fb06fbd336f8ca38043d56d62f
Author: Gauthier Ambard <gambard@chromium.org>
Date: Wed Mar 28 13:49:38 2018

Add animations for the popup menus

This CL adds the present/dismiss animations for the popup menus.
It also modifies the general positioning of the popup.

Bug:  804772 , 804776 
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I9ed5780079f5d6d40ef3f9c919f22825f4969a17
Reviewed-on: https://chromium-review.googlesource.com/983552
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546471}
[modify] https://crrev.com/2eab8d34fcdf23fb06fbd336f8ca38043d56d62f/ios/chrome/browser/ui/popup_menu/popup_menu_presenter.mm
[modify] https://crrev.com/2eab8d34fcdf23fb06fbd336f8ca38043d56d62f/ios/chrome/browser/ui/popup_menu/popup_menu_view_controller.mm