Chrome Version: Google Chrome 71.0.3578.98
Chrome OS Version: Platform 11151.61.0 (Official Build) stable-channel eve
Chrome OS Platform: Eve

Steps To Reproduce:
(1) Start crostini
(2) sudo apt-get install weston
(3) /usr/lib/weston/weston-scaler -s

Expected Result: A mostly blue square (compare to running the same app inside weston).

Actual Result: A red border around the left and top of the square. This seems to be because the viewport params sent to the host doesn't include buffer scale and sommelier doesn't assign buffer scale on the host buffer.

How frequently does this problem reproduce? Always

What is the impact to the user, and is there a workaround? If so, what is it?

I've only seen this in a test app. But any application that combined wl_surface::set_buffer_scale and wp_viewport may draw incorrectly.

Please provide any additional information below. Attach a screen shot or log if possible.