How should we handle lines with two fields, like credit cards expiration.  For example
07 / 21

Only the farthest right would be tap-able all the way. In your example, the 07 tappable area stays as it is now, only the 21 would grow.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f9d0a2bb4c9ba2ffe890c4a69a54aa3f9e17a426

commit f9d0a2bb4c9ba2ffe890c4a69a54aa3f9e17a426
Author: David Jean <djean@google.com>
Date: Fri Nov 23 17:00:27 2018

[ios] make manual fallback buttons larger and with touch highlight

Bug:  907082 ,907001
Change-Id: I30d4a9f0a1463f3b500cefc255b4335bde790b37
Reviewed-on: https://chromium-review.googlesource.com/c/1348109
Reviewed-by: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Commit-Queue: David Jean <djean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610637}
[modify] https://crrev.com/f9d0a2bb4c9ba2ffe890c4a69a54aa3f9e17a426/ios/chrome/browser/ui/autofill/manual_fill/BUILD.gn
[modify] https://crrev.com/f9d0a2bb4c9ba2ffe890c4a69a54aa3f9e17a426/ios/chrome/browser/ui/autofill/manual_fill/manual_fill_address_cell.mm
[modify] https://crrev.com/f9d0a2bb4c9ba2ffe890c4a69a54aa3f9e17a426/ios/chrome/browser/ui/autofill/manual_fill/manual_fill_card_cell.mm
[add] https://crrev.com/f9d0a2bb4c9ba2ffe890c4a69a54aa3f9e17a426/ios/chrome/browser/ui/autofill/manual_fill/manual_fill_cell_button.h
[add] https://crrev.com/f9d0a2bb4c9ba2ffe890c4a69a54aa3f9e17a426/ios/chrome/browser/ui/autofill/manual_fill/manual_fill_cell_button.mm
[modify] https://crrev.com/f9d0a2bb4c9ba2ffe890c4a69a54aa3f9e17a426/ios/chrome/browser/ui/autofill/manual_fill/manual_fill_cell_utils.h
[modify] https://crrev.com/f9d0a2bb4c9ba2ffe890c4a69a54aa3f9e17a426/ios/chrome/browser/ui/autofill/manual_fill/manual_fill_cell_utils.mm
[modify] https://crrev.com/f9d0a2bb4c9ba2ffe890c4a69a54aa3f9e17a426/ios/chrome/browser/ui/autofill/manual_fill/manual_fill_password_cell.mm