Issue 750736  has been merged into this issue.

https://chromium-review.googlesource.com/c/593012 will land soon for a related test.

However, there seems to be need for manual testing as well. Plans for that should be made at some point. vabr@ will be happy to work on those once back.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e7acbb190061307931922e4441931e7d06bf56ba

commit e7acbb190061307931922e4441931e7d06bf56ba
Author: Vaclav Brozek <vabr@chromium.org>
Date: Wed Nov 15 17:40:34 2017

Update TestPasswordStore with NOTIMPLEMENTED

This CL updates the documentation of TestPasswordStore to
reflect which functionality is implemented and which is not.

Bug:  750884 
Change-Id: I87fae2550cb8a5714604bed678b4cb6b7de109af
Reviewed-on: https://chromium-review.googlesource.com/771155
Commit-Queue: Vaclav Brozek <vabr@chromium.org>
Reviewed-by: Vadym Doroshenko <dvadym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516737}
[modify] https://crrev.com/e7acbb190061307931922e4441931e7d06bf56ba/components/password_manager/core/browser/test_password_store.cc
[modify] https://crrev.com/e7acbb190061307931922e4441931e7d06bf56ba/components/password_manager/core/browser/test_password_store.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5b3fb062094a6bc5c6b6157cc9ba3cd01e6e0b9a

commit 5b3fb062094a6bc5c6b6157cc9ba3cd01e6e0b9a
Author: Vaclav Brozek <vabr@chromium.org>
Date: Thu Nov 16 10:20:59 2017

Test "below-the-fold" passwords in iOS settings

This CL adds a test for handling a bigger number of stored
passwords in iOS settings than how much fit on a single screen.

Bug:  750884 
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I459ecbda1ad18b046ba54652c2fb393c51c708e2
Reviewed-on: https://chromium-review.googlesource.com/593012
Commit-Queue: Vaclav Brozek <vabr@chromium.org>
Reviewed-by: Mike Baxley <baxley@chromium.org>
Reviewed-by: Mike Pinkerton <pinkerton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517045}
[modify] https://crrev.com/5b3fb062094a6bc5c6b6157cc9ba3cd01e6e0b9a/ios/chrome/browser/ui/settings/passwords_settings_egtest.mm

The code changes are done and I contacted Lindsay about the manual scenario.

vabr@, Can you please add the manual scenario here, so test team  can test this.

Copying out of my e-mail to lindsayw@ from 15 November:

-------------------------------------
I propose the following script:
  (1) Open Chrome, set up sync for <test-account> (more on the account below) to get a 1000 of saved passwords through sync.
  (2) Once sync completes, open Settings -> Save Passwords.
  (3) Scroll down to verify that 1000 password entries are present (they will be numbered to make this easy); check that scrolling is smooth and the UI stays responsive.
  (4) Tap on an entry roughly in the middle of the list. Check that the detailed view is opened quickly and the username in the details matches the one of the selected entry.
  (5) Close settings by tapping the back arrow in the top-left corner twice. Check that the UI reacts quickly and stays responsive.

As for the test account, I'm happy to initialise it with the list of passwords. I can also create a new testing one and pass it to you, but for that I'd like to know which MDB group (send by e-mail, don't share on the public bug) I can use for owning that test account, so that relevant people become owners. Alternatively, I can populate a test account of your choice.
-------------------------------------

Verified in 64.0.3279.0 canary, iPhone 6 iOS 10.3.3, iPhone 7 iOS11.2 beta 4,

Followed the steps comment #7, looks good.

We have found 2 issues that were not mentioned in the test scenarios:
788843, 788849