Version: ALL
OS: Chrome OS

What steps will reproduce the problem?
(1)  Connect four monitors to a Chrome device (1xHDMI, 1xDP, 2xUDL 3.0)
(2)  Verify expanded desktop works properly, and that monitor arrangement works correctly in Display Settings
(3)  Enable unified desktop mode
(4)  In Display Settings, monitor arrangement is disabled and no longer possible.

What is the expected output? What do you see instead?

We expect to be able to arrange monitors.  Currently, with unified desktop enabled, we are unable to arrange screens in anything other than a continuous horizontal arrangement that is determined by CrOS when unified desktop is enabled.  We see one large desktop that is 4 monitors wide.  We need it to be two wide by two tall (3840x2160 final resolution).  Other OS's can do this.

Use case: Customer has a 2x2 video wall, the desire is to use a Chrome device with unified desktop so they can design/display content for one large canvas.