This is a tracking bug for making the code in //ash/system/tray use ash::wm::WmWindow instead of aura::Window directly.
For mash, we're starting to collapse the window manager (desktop_wm) and system UI (ash_sysui) into a single process/service. The window manager bits manipulate mus windows, via a wrapper class ash::wm::WmWindow.
In order to make the status tray work in this environment it will need to avoid direct access to aura::Window and use the wrappers instead.
As things are converted they will move into //ash/common/system/tray
Comment 1 by bugdroid1@chromium.org
, Jun 13 2016