The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e8ce3a42b2e85fe2b82dbbb1c43c115d1f51de74

commit e8ce3a42b2e85fe2b82dbbb1c43c115d1f51de74
Author: Aga Wronska <agawronska@chromium.org>
Date: Tue Jan 23 20:22:35 2018

Add support for 6+ users in views based login.

Separate logic for creating users list (small and extra small
display style) into ScrollableUsersListView.
ScrollableUsersListView:
* is initialized with appropriate params in LockContentsView
* adjusts its insets according to device orientation
* provides functionality to draw gradient at the top and bottom of the
background

Bug:  792742 
Change-Id: I1d6087f7332261044a2d896b328570da124b9eb2
Reviewed-on: https://chromium-review.googlesource.com/875150
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Commit-Queue: Aga Wronska <agawronska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531328}
[modify] https://crrev.com/e8ce3a42b2e85fe2b82dbbb1c43c115d1f51de74/ash/BUILD.gn
[modify] https://crrev.com/e8ce3a42b2e85fe2b82dbbb1c43c115d1f51de74/ash/login/ui/layout_util.cc
[modify] https://crrev.com/e8ce3a42b2e85fe2b82dbbb1c43c115d1f51de74/ash/login/ui/layout_util.h
[modify] https://crrev.com/e8ce3a42b2e85fe2b82dbbb1c43c115d1f51de74/ash/login/ui/lock_contents_view.cc
[modify] https://crrev.com/e8ce3a42b2e85fe2b82dbbb1c43c115d1f51de74/ash/login/ui/lock_contents_view.h
[modify] https://crrev.com/e8ce3a42b2e85fe2b82dbbb1c43c115d1f51de74/ash/login/ui/lock_contents_view_unittest.cc
[add] https://crrev.com/e8ce3a42b2e85fe2b82dbbb1c43c115d1f51de74/ash/login/ui/scrollable_users_list_view.cc
[add] https://crrev.com/e8ce3a42b2e85fe2b82dbbb1c43c115d1f51de74/ash/login/ui/scrollable_users_list_view.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9ab73de940884828d3908361837a35d0fb072263

commit 9ab73de940884828d3908361837a35d0fb072263
Author: Aga Wronska <agawronska@chromium.org>
Date: Mon Jan 29 16:05:53 2018

Update scroll bar in 6+ login view  to match the mocks.

Update color of scroll bar and make the edges of scroll thumb rounded.
Show scroll bar only upon hover.

Bug:  792742 
Change-Id: I80f88e9e0ffe16202401e385593bcc736840a2f2
Reviewed-on: https://chromium-review.googlesource.com/887249
Commit-Queue: Aga Wronska <agawronska@chromium.org>
Reviewed-by: Jacob Dufault <jdufault@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532444}
[modify] https://crrev.com/9ab73de940884828d3908361837a35d0fb072263/ash/login/ui/scrollable_users_list_view.cc
[modify] https://crrev.com/9ab73de940884828d3908361837a35d0fb072263/ash/login/ui/scrollable_users_list_view.h