Headrest Pillow

FIG. 1 is a perspective view of a headrest pillow showing our new design. FIG. 2 is another perspective view shown in a use state with environment, with the buckle shown in an open position. FIG. 3 is a front view thereof. FIG. 4 is a rear view thereof. FIG. 5 is a left side view thereof. FIG. 6 is a right side view thereof. FIG. 7 is a top view thereof. FIG. 8 is a bottom view thereof; and, FIG. 9 is a rear perspective view of a headrest pillow, shown in a use state with environment. The broken lines illustrate portions of the headrest pillow that form no part of the claimed design. The broken lines in FIG. 2 and FIG. 9 indicate environmental structure and form no part of the claimed design.