I can see tearing in most of the content on my Chromebook eve
on ToT. Can see it anywhere in the UI if I just hover and move
around the mouse , but is particularly evident with video playback,
e.g. with http://crosvideo.appspot.com/?codec=vp9&loop=true&mute=true&cycle=true

This is on a developer build 68.0.3402.0 (r552331) on a 10594 OS (official build).