The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/18d5a836fc93923c50d6e1f060e67c6bf037876d

commit 18d5a836fc93923c50d6e1f060e67c6bf037876d
Author: Gauthier Ambard <gambard@chromium.org>
Date: Fri Apr 06 13:38:07 2018

Add metric for the opening of popup menu

This CL adds a metrics for the time elapsed between the time the user
taps on a button and the popup menu is presented.

Bug:  829343 
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Id978bd57ffa93adc0827a7810ca546c8272aded7
Reviewed-on: https://chromium-review.googlesource.com/999476
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548763}
[modify] https://crrev.com/18d5a836fc93923c50d6e1f060e67c6bf037876d/ios/chrome/browser/ui/download/download_manager_coordinator.mm
[modify] https://crrev.com/18d5a836fc93923c50d6e1f060e67c6bf037876d/ios/chrome/browser/ui/popup_menu/BUILD.gn
[modify] https://crrev.com/18d5a836fc93923c50d6e1f060e67c6bf037876d/ios/chrome/browser/ui/popup_menu/popup_menu_coordinator.mm
[modify] https://crrev.com/18d5a836fc93923c50d6e1f060e67c6bf037876d/ios/chrome/browser/ui/popup_menu/popup_menu_presenter.mm
[modify] https://crrev.com/18d5a836fc93923c50d6e1f060e67c6bf037876d/ios/chrome/browser/ui/presenters/contained_presenter_delegate.h
[modify] https://crrev.com/18d5a836fc93923c50d6e1f060e67c6bf037876d/ios/chrome/browser/ui/presenters/vertical_animation_container.mm
[modify] https://crrev.com/18d5a836fc93923c50d6e1f060e67c6bf037876d/ios/chrome/browser/ui/presenters/vertical_animation_container_unittest.mm
[modify] https://crrev.com/18d5a836fc93923c50d6e1f060e67c6bf037876d/ios/chrome/browser/ui/translate/language_selection_coordinator.mm