We claim the ornamental design for an electronic device, as shown and described.
FIG. 1 is a front perspective view of an electronic device, showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left-side view thereof;
FIG. 5 is a right-side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines illustrating portions of the electronic device are for environmental purposes only and form no part of the claimed design. The dot-dash lines in the figures represent an unclaimed boundary line and form no part of the claimed design.