The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/780ed524823d11e245f40c2f68ebf03a0b2c3ee0

commit 780ed524823d11e245f40c2f68ebf03a0b2c3ee0
Author: Jérôme Lebel <jlebel@chromium.org>
Date: Wed Jul 19 07:34:46 2017

Record Signin_ImpressionWithAccount_From* and Signin_ImpressionWithNoAccount_From*

Adding user action metrics to record impression for the new sign-in promo
view when it is shown with a default account or without a default account.

Bug:  742332 
Change-Id: Ic095395f037790b4ff887d29fc7c2edeaffb304a
Reviewed-on: https://chromium-review.googlesource.com/576091
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487781}
[modify] https://crrev.com/780ed524823d11e245f40c2f68ebf03a0b2c3ee0/ios/chrome/browser/ui/authentication/signin_promo_view_mediator.mm
[modify] https://crrev.com/780ed524823d11e245f40c2f68ebf03a0b2c3ee0/tools/metrics/actions/actions.xml