Chrome Version: 72.0.3620.0
OS: Windows 10.0.17134

What steps will reproduce the problem?
(1) Set display scale to 125% or 250% (I tested 1920x1080 125%, 3840x2160 125%, and 3840x2160 250%)
(2) Run with --enable-features="UiGpuRasterization<GpuRasterForUi" (with new user-data-dir)
(3) Maximize Chrome window

There is a ~2px black line between the browser ui (omnibar) and the page content. There is ANOTHER ~1px black line below that sometimes (it's not always there), which flickers.

When the second black line flickers, it also causes my mouse cursor to jump (looks like it misses a few frames).

This reproduces on both my Win/Intel laptop and on zmo's Win/NVIDIA workstation.

(Huge thanks to zmo for his variations bisect script https://crrev.com/c/1335272 , which allowed us to narrow down the issue!)
 

Deleted: VID_20181124_130835.mp4 8.7 MB

	VID_20181124_130835.mp4 8.7 MB View Download

Deleted: aboutgpu.txt 12.1 KB

aboutgpu.txt 12.1 KB View Download