This is working on desktop and hence likely to be fixed once we start sharing desktop heuristics with iOS code.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/75c63e7a07f0dbdf77372e4aeff543eee680e463

commit 75c63e7a07f0dbdf77372e4aeff543eee680e463
Author: Vadym Doroshenko <dvadym@chromium.org>
Date: Fri Aug 25 12:54:26 2017

[Bling Password Manager] Send request to browser on input onFocus.

Password Manager on other platforms listens to DOM changes in order to detect dynamically added forms. In Bling there is no such mechanism. 

This CL adds mitigation for this, namely if the user clicks on an input element and no password forms found on this page, Password Manager would try to find password forms. So this CL would allow to process dynamically added forms in principle, both for filling (when the user clicks) and saving (if the form is not found, it would be skipped on submission in PasswordManager, since in the current architecture PasswordFormManager should be created before submission). 

The request to the password store on the focus is sent only once for a page, and that's controlled by |sent_request_to_store_| variable.

Bug:  708597 ,  709011 ,  708634 
Change-Id: Ie47f6335c6c7681dadfef7b53276007527e400c4
Reviewed-on: https://chromium-review.googlesource.com/601969
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Commit-Queue: Vadym Doroshenko <dvadym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#497383}
[modify] https://crrev.com/75c63e7a07f0dbdf77372e4aeff543eee680e463/ios/chrome/browser/passwords/password_controller.mm
[modify] https://crrev.com/75c63e7a07f0dbdf77372e4aeff543eee680e463/ios/chrome/browser/passwords/password_controller_unittest.mm

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/680972d7f662ac2414aaa8fa73f66cacf9e88c9b

commit 680972d7f662ac2414aaa8fa73f66cacf9e88c9b
Author: Vadym Doroshenko <dvadym@chromium.org>
Date: Thu Mar 01 17:31:40 2018

[IOS Password Manager] Async suggestions retrieval.

When a password form is added dynamically (i.e. with JavaScript after finishing of a page load)
IOS Password Manager may learn about existing of this form only after user clicking on
some field in this form. On CL https://chromium-review.googlesource.com/c/chromium/src/+/601969
it was implemented retrieving credentials from the Password Store as soon as the user clicked
on dynamically added form and then credentials are autofilled. But fill on account select is not
available until the user makes another interaction with the form (for example start typing of
username). That's suboptimal user experience, it would be good to propose fill on
account select immediately as soon as the user clicks the first time in the form.

This CL implements async suggestion response to Autofill framework in the same way as it's
already implemented in Autofill:
1.When checkIfSuggestionsAvailableForForm (password_controller.mm) is called, and it's
found that credentials haven't been retrieved yet for this page, the callback is saved
untile response from the Password Store is received.
2.It's implemented that Password Store response is propagated to PasswordController even if case
when there are no credentials saved for this page in order to inform Autofill framework that
no suggestions are available.

Bug:  708597 ,  709011 ,  708634 
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Idecc3e621100f3e1b0a3803ce944c4cc116fc3a4
Reviewed-on: https://chromium-review.googlesource.com/921961
Commit-Queue: Vadym Doroshenko <dvadym@chromium.org>
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#540200}
[modify] https://crrev.com/680972d7f662ac2414aaa8fa73f66cacf9e88c9b/components/password_manager/core/browser/password_form_manager.cc
[modify] https://crrev.com/680972d7f662ac2414aaa8fa73f66cacf9e88c9b/components/password_manager/core/browser/password_form_manager_unittest.cc
[modify] https://crrev.com/680972d7f662ac2414aaa8fa73f66cacf9e88c9b/components/password_manager/core/browser/password_manager_driver.h
[modify] https://crrev.com/680972d7f662ac2414aaa8fa73f66cacf9e88c9b/ios/chrome/browser/passwords/ios_chrome_password_manager_driver.h
[modify] https://crrev.com/680972d7f662ac2414aaa8fa73f66cacf9e88c9b/ios/chrome/browser/passwords/ios_chrome_password_manager_driver.mm
[modify] https://crrev.com/680972d7f662ac2414aaa8fa73f66cacf9e88c9b/ios/chrome/browser/passwords/password_controller.mm
[modify] https://crrev.com/680972d7f662ac2414aaa8fa73f66cacf9e88c9b/ios/chrome/browser/passwords/password_controller_unittest.mm

The mobile site url is fuzzy matched to Desktop, that means it could be filled only on account select, i.e. by clicking on the username field and choosing username from keyboard accessories. Now it works.

Now the username and password appear to get written in, but the site is showing errors like no username and password have been entered. Please see screenshot.
https://drive.google.com/file/d/1fbOGayCh4cWsGlg576sls1x6hJl27rG4/view