For 'Use ripple circle as keyboard focus indicator', I can only think of adding dummy ripples for each digit, which may look ugly in codes. For 'Slightly longer ripple animation', I think it's in third party codes. Are these two must-have?

The other two can be done easily.

Longer is not a must-have. We do need a better focus indicator though, so dummy ripples may be the way to go.

I just recall that using 'Tab' to enter password via PIN keyboard is not really working. This is a known bug and existed even before the UI refresh ( crbug.com/734732 ).

I spent some time digging into this a while ago but couldn't fix it. Later we decided to punt it because if user have access to tab they should normally be able to use the digit buttons. (unless, one of the digit buttons is broken..)

So the 'focused' in PIN is not meaningful as of now. What do you think?
 

Okay makes sense. Can we fix in Views lockscreen?

Most likely yes.  crbug.com/734732  will be left open to track this.

I've continued looking into the issue but if there's no fix before M61, do we still want to enable focusing on digits at all?

Yes, we should still allow it for accessibility use cases.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4b1b41347f0afe0abf358c1c1237ff563132b571

commit 4b1b41347f0afe0abf358c1c1237ff563132b571
Author: Wenzhao Zang <wzang@chromium.org>
Date: Thu Aug 10 05:22:18 2017

Adjust smart lock bubble position and PIN keyboard ripple size

In response to the second round of UI review:

1) Refactor the codes to reuse the error bubble codes for smart lock
bubble.

2) Adjust PIN keyboard ripple size and color.

Bug:  753429 ,  753426 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I7f48b52b3cf66d150b227e6ff6d2f01f7ca80710
Reviewed-on: https://chromium-review.googlesource.com/607713
Commit-Queue: Wenzhao (Colin) Zang <wzang@chromium.org>
Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#493261}
[modify] https://crrev.com/4b1b41347f0afe0abf358c1c1237ff563132b571/chrome/browser/resources/chromeos/quick_unlock/md_pin_keyboard.html
[modify] https://crrev.com/4b1b41347f0afe0abf358c1c1237ff563132b571/ui/login/account_picker/md_screen_account_picker.js
[modify] https://crrev.com/4b1b41347f0afe0abf358c1c1237ff563132b571/ui/login/account_picker/md_user_pod_row.js

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3d8444b4839743cb1a510fb102e23b61200d8f73

commit 3d8444b4839743cb1a510fb102e23b61200d8f73
Author: Wenzhao Zang <wzang@chromium.org>
Date: Thu Aug 10 18:53:58 2017

Adjust smart lock bubble position and PIN keyboard ripple size

In response to the second round of UI review:

1) Refactor the codes to reuse the error bubble codes for smart lock
bubble.

2) Adjust PIN keyboard ripple size and color.

TBR=wzang@chromium.org

(cherry picked from commit 4b1b41347f0afe0abf358c1c1237ff563132b571)

Bug:  753429 ,  753426 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I7f48b52b3cf66d150b227e6ff6d2f01f7ca80710
Reviewed-on: https://chromium-review.googlesource.com/607713
Commit-Queue: Wenzhao (Colin) Zang <wzang@chromium.org>
Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#493261}
Reviewed-on: https://chromium-review.googlesource.com/610935
Reviewed-by: Wenzhao (Colin) Zang <wzang@chromium.org>
Cr-Commit-Position: refs/branch-heads/3163@{#449}
Cr-Branched-From: ff259bab28b35d242e10186cd63af7ed404fae0d-refs/heads/master@{#488528}
[modify] https://crrev.com/3d8444b4839743cb1a510fb102e23b61200d8f73/chrome/browser/resources/chromeos/quick_unlock/md_pin_keyboard.html
[modify] https://crrev.com/3d8444b4839743cb1a510fb102e23b61200d8f73/ui/login/account_picker/md_screen_account_picker.js
[modify] https://crrev.com/3d8444b4839743cb1a510fb102e23b61200d8f73/ui/login/account_picker/md_user_pod_row.js

The above CL points to another issue https://bugs.chromium.org/p/chromium/issues/detail?id=753429

which gets merge approval.

This one is not fixed yet, we still have:
- Slightly longer ripple animation
- Use ripple circle as kebyoard focus indicator

They are not likely to make 61, but will be fixed for views-based lock screen.

Issue 755288 has been merged into this issue.