FIG. 1 is a first side view of an ornamental design of an embodiment of a bottom portion housing for a mobile device showing our new design;
FIG. 2 is a second side view thereof;
FIG. 3 is a third view thereof;
FIG. 4 is a foruth view thereof;
FIG. 5 is a fifth side view thereof;
FIG. 6 is a sixth side view thereof; and,
FIG. 7 is an isometric view thereof.
The broken lines shown in FIGS. 1-7 are included for illustrative purposes only and form no part of the claimed design.