I claim the ornamental design for a sliding chair base, as shown and described.
FIG. 1 is a top perspective view of a sliding chair base showing my new design, in accordance with the present invention;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is a front elevational view thereof, the back, right side and left side being identical images thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof; and,
FIG. 6 is a cross-sectional view taken through line 6-6 of FIG. 4.
The furniture shown in broken lines attached to the sliding chair base in FIG. 1 is shown for environmental use purposes only, and forms no part of the claimed design. The central portion of the sliding chair base illustrated in FIGS. 2, 4, 5 and 6 is illustrated in broken line for illustration purposes only, and as such, form no part of the claimed design. The cross-section of FIG. 3 is illustrated to more clearly show the curvature of the bottom of the sliding chair base. The cross-section passes through the center point such that the front, back, right side and left side views are identical images to one another.