Chrome Version: <From about:version: Google Chrome 65.0.3325.209>
Chrome OS Version: <From about:version: Platform 10323.67.0>
Chrome OS Platform: <Samsung Chrome Plus>
Network info: <not relevant>

Please specify Cr-* of the system to which this bug/feature applies (add
the label below).

Steps To Reproduce:
(1) try to choose a keyboard layout
(2) there's us, us-intl, but no us-macintosh
(3)

Expected Result:
Be able to select us-macintosh

Actual Result:

How frequently does this problem reproduce? 
Always

What is the impact to the user, and is there a workaround? If so, what is
it?
no workaround available

This is a standard X11 keyboard layout variant, that allows you to use alt-gr/option for doing accents - for developers this is a lifesaver, since doing [',"] with us-intl(deadkeys) is annoying.

TL;DR need to write both english and portuguese, that would be useful.

model:      pc105
layout:     us
variant:    mac