The ornamental design for a trayassembly for a seating unit, as shown.
The FIGURE is a perspective view of top, front, and one side of a tray
assembly for a seating unit showing my new design it being understood that
the broken lines are for illustrative purposes only and form no part of
the claimed design.
The surface(s) or portion(s) of the article not shown in the drawing or
described in the specification form(s) no part of the claimed design.