Chrome Version       : 64.0.3280.5
OS Version: 10172.0.0

What steps will reproduce the problem?
1. Open pretty much any page (e.g., Gmail, crbug.com, etc) on a ChromeBook Pixel.
2. Interact with the page in a way that requires a partial redraw (scroll, enter text, move cursor, etc).
3. See large black rectangles or missing content (white).

This started in a previous dev channel version on 64 (note: omahaproxy data for ChromeOS seems to be stale).

It makes the machine almost unusable. Sometimes the current element is black -- As I type this the text input element for this bug is ok, but everything around is flashing black on and off with each keystroke or in sync with the cursor flashing. Switching to another tab and switching back usually makes it go away temporarily. Looks like a frontbuffer/backbuffer problem.