UserAgent: Mozilla/5.0 (X11; CrOS x86_64 11021.56.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.76 Safari/537.36
Platform: 11021.56.0 (Official Build) stable-channel edgar

Steps to reproduce the problem:
1. Set shelf to autohide
2. Set shelf position to the left 
3. Hover the cursor to the left side of the screen while Chrome Browser is opened

What is the expected behavior?

What went wrong?
During the animation process after the cursor hovers onto the shelf, the top and bottom corners of the shelf produce screen tears that persist until cursor is moved away from shelf.

Did this work before? N/A 

Chrome version: 70.0.3538.76  Channel: stable
OS Version: 11021.56.0
Flash Version: 

This wasn't until the shelf ui changed to have rounded corners.