The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1b44ef4b1154ef2609a31dde665c100a51ce54a6

commit 1b44ef4b1154ef2609a31dde665c100a51ce54a6
Author: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Date: Thu Nov 29 13:03:04 2018

[iOS][MF] Add histograms

Adds histograms for:
How many autofill suggestions exists when a user opens passwords manual fallback.
How many autofill suggestions exists when a user opens credit cards manual fallback.
How many autofill suggestions exists when a user opens profiles manual fallback.

Bug:  905653 ,  845472 
Change-Id: I114fee74ea1f78a8fe08b3e8a373fa8946e0d7ae
Reviewed-on: https://chromium-review.googlesource.com/c/1352166
Commit-Queue: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612166}
[modify] https://crrev.com/1b44ef4b1154ef2609a31dde665c100a51ce54a6/ios/chrome/browser/autofill/form_input_accessory_view_controller.mm
[modify] https://crrev.com/1b44ef4b1154ef2609a31dde665c100a51ce54a6/tools/metrics/histograms/histograms.xml