Steps to reproduce:
- Ensure that autocomplete has a profile with an email address
- Visit a login form in which the username is annotated with autocomplete="email"
- First type a password
- Then choose a username via autocomplete

Observe that the password manager is not notified about the chosen username. The same happens if you type a character of the email address and then pick an autocomplete choice. The password manager captures only the typed characters.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a332ebc6a944a16cee8726c18a986cfd61288f11

commit a332ebc6a944a16cee8726c18a986cfd61288f11
Author: Vadym Doroshenko <dvadym@chromium.org>
Date: Thu Sep 14 11:46:53 2017

AutofillAgent informs PasswordAutofillAgent about filling.

On each change in text field, PasswordAutofillAgent saves provisionally username/password as candidates for saving. If PasswordAutofillAgent is not informed about filling from AutofillAgent it might miss autofill value and propose incorrect value to save. 

Bug:  763909 
Change-Id: I7abaca7eb1c3f9686df29f7d2e83f2b88a72401b
Reviewed-on: https://chromium-review.googlesource.com/663361
Reviewed-by: Maxim Kolosovskiy <kolos@chromium.org>
Reviewed-by: Roger McFarlane <rogerm@chromium.org>
Commit-Queue: Maxim Kolosovskiy <kolos@chromium.org>
Commit-Queue: Vadym Doroshenko <dvadym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501922}
[modify] https://crrev.com/a332ebc6a944a16cee8726c18a986cfd61288f11/chrome/renderer/autofill/password_autofill_agent_browsertest.cc
[modify] https://crrev.com/a332ebc6a944a16cee8726c18a986cfd61288f11/components/autofill/content/renderer/autofill_agent.cc

This is very simple (1 line in production code) and non-risky patch, that fixes pretty inconvenient cases when Password Manager offers to save incorrect username.

This bug requires manual review: M62 has already been promoted to the beta branch, so this requires manual review
Please contact the milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), bhthompson@(ChromeOS), abdulsyed@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Per comment 5, it's a small simple patch. Approving merge to M62. Branch: 3202

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0648996a7584cc6f3aa1f350206dd6dd0f3863a1

commit 0648996a7584cc6f3aa1f350206dd6dd0f3863a1
Author: Vadym Doroshenko <dvadym@chromium.org>
Date: Tue Sep 19 10:03:40 2017

[Merge to M62]AutofillAgent informs PasswordAutofillAgent about filling.

On each change in text field, PasswordAutofillAgent saves provisionally username/password as candidates for saving. If PasswordAutofillAgent is not informed about filling from AutofillAgent it might miss autofill value and propose incorrect value to save.

TBR=dvadym@chromium.org

(cherry picked from commit a332ebc6a944a16cee8726c18a986cfd61288f11)

Bug:  763909 
Change-Id: I7abaca7eb1c3f9686df29f7d2e83f2b88a72401b
Reviewed-on: https://chromium-review.googlesource.com/663361
Reviewed-by: Maxim Kolosovskiy <kolos@chromium.org>
Reviewed-by: Roger McFarlane <rogerm@chromium.org>
Commit-Queue: Maxim Kolosovskiy <kolos@chromium.org>
Commit-Queue: Vadym Doroshenko <dvadym@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#501922}
Reviewed-on: https://chromium-review.googlesource.com/671355
Reviewed-by: Vadym Doroshenko <dvadym@chromium.org>
Cr-Commit-Position: refs/branch-heads/3202@{#318}
Cr-Branched-From: fa6a5d87adff761bc16afc5498c3f5944c1daa68-refs/heads/master@{#499098}
[modify] https://crrev.com/0648996a7584cc6f3aa1f350206dd6dd0f3863a1/chrome/renderer/autofill/password_autofill_agent_browsertest.cc
[modify] https://crrev.com/0648996a7584cc6f3aa1f350206dd6dd0f3863a1/components/autofill/content/renderer/autofill_agent.cc