The ornamental design for a scrubbrush, as shown and described.
FIG. 1 is a top perspective view of a scrub brush;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof;
FIG. 5 is a right side elevational view thereof; and,
FIG. 6 is a front elevational view thereof.
The broken lines shown in the drawings illustrate features of the article in which the design is embodied that form no part of the claim.
A left side elevational view is not shown because it is identical to the right side elevational view shown in FIG. 5. A rear elevational view is not shown because it is identical to the front elevational view shown in FIG. 6.