We claim the ornamental design for case for mobile device, as shown and described.
FIG. 1 is a front perspective view of the case for mobile device;
FIG. 2 is another front perspective view of the case for mobile device shown in FIG. 1;
FIG. 3 is rear perspective view of the case for mobile device shown in FIG. 1;
FIG. 4 is a front plan view of the case for mobile device shown in FIG. 1;
FIG. 5 is rear plan view of the case for mobile device shown in FIG. 1;
FIG. 6 is a left plan view of the case for mobile device shown in FIG. 1;
FIG. 7 is a right plan view of the case for mobile device shown in FIG. 1;
FIG. 8 is a top plan view of the case for mobile device shown in FIG. 1; and,
FIG. 9 is a bottom plan view of the case for mobile device shown in FIG. 1.
The portions of the case for a mobile device shown in dashed lines, and any surfaces of the design not shown, including interior surfaces, form no part of the claimed design.