The ornamental design for a mobilestoragedevice, as shown and described.
FIG. 1 is a perspective view of a mobile storage device showing my new design.
FIG. 2 is a front elevational view thereof.
FIG. 3 is a rear elevational view thereof.
FIG. 4 is a left side elevational view thereof.
FIG. 5 is a right side elevational view thereof.
FIG. 6 is a top plan view thereof.
FIG. 7 is a bottom plan view thereof.
FIG. 8 is a perspective view of a first open state thereof; and,
FIG. 9 is a perspective view of a second open state thereof.
The broken line immediately adjacent to the solid line shown in FIGS. 8 and 9 defines the bounds of the claimed design. The broken lines showing the USB connector and various portions are for the purpose of illustrating unclaimed portions. The broken lines form no part of the claimed design.