The ornamental design for a chairbase, as shown and described.
This application is related to design patent application Ser. Nos. 29/305/602; 29/305,603; 29/305,605; 29/305,606; 29/305,607; 29/305,610; and 29/305,615, which are filed concurrently herewith.
FIG. 1 is a perspective view showing the front, left side, and top of a chair base which forms my new design, the broken lines of a chair and casters being for illustrative purposes only and forming no part of my design;
FIG. 2 is an enlarged perspective view thereof;
FIG. 3 is an enlarged top plan view thereof; and,
FIG. 4 is an enlarged front elevational view thereof.