The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ce3e74bd59411bcd3c795f7f1d87b697463cd2a4

commit ce3e74bd59411bcd3c795f7f1d87b697463cd2a4
Author: wzang <wzang@chromium.org>
Date: Thu Jun 15 19:22:24 2017

Update easy unlock icon assets for new signin screen

The background of the easy unlock icon changes from white to transparent
in the new MD signin screen.

The link to the spec for reference: https://gallery.googleplex.com/projects/MCHbtQVoQ2HCZdwfnbqy2eSi/files/MCHm5Lyh8lQ6SZ3vjzwd3Uo8wMSJbxAVNpw

BUG= 718159 ,  718172 

Review-Url: https://codereview.chromium.org/2934193002
Cr-Commit-Position: refs/heads/master@{#479777}

[modify] https://crrev.com/ce3e74bd59411bcd3c795f7f1d87b697463cd2a4/ui/resources/default_100_percent/common/easy_unlock_spinner.png
[modify] https://crrev.com/ce3e74bd59411bcd3c795f7f1d87b697463cd2a4/ui/resources/default_200_percent/common/easy_unlock_spinner.png

I think the new assets you landed are not properly aligned for the animation. I'm seeing a jittery animation in which part of the previous frame is being included in the current frame during the animation.

I'm not sure how to take a video of this on the lock screen, but I would be happy to help repro.

tengs@, thanks for pointing it out. I saw CL 2956543002 adds a padding, will it solve the jittery animation problem completely?

No. I think the jittery animation is due to an issue in the png, which isn't completely aligned correctly for each frame.

Is it the .custom-icon-spinner in 
https://cs.chromium.org/chromium/src/ui/login/account_picker/md_user_pod_row.css?q=md_user_pod_row.css&dr

Yes that's right. A easy way to test is simply setting that class in the devtools inspector.

Also based on the specs, it seems the icon needs to be smaller.

tengs, is this video the same with what's shown on your device? I'm not really seeing any jarring animation issue. Besides, I'm aware that it's different from the specs but it's approved by UI.

Deleted: VID_20170623_134815.mp4 10.0 MB

	VID_20170623_134815.mp4 10.0 MB View Download

Ah it turns out the problem is changing the resolution on the screen.

The asset works in some (most?) resolutions, but when I toggle through the resolutions using Ctrl+Shift+{+/-}, it's noticeable that the animation is unsmooth in certain resolutions.

It is observable for me on the 1536x864 resolution.

Here is a video of the animation.

Deleted: VID_20170707_150121.mp4 15.2 MB

VID_20170707_150121.mp4 15.2 MB Download

It seems the padding is also missing in this resolution.

My initial thought is that the user pod's size is scaling based on the resolution, which breaks a lot of the relative sizing used in the css.

 Issue 735646  has been merged into this issue.