The ornamental design for a painttrayliner, as shown and described.
FIG. 1 is a top view of the liner;
FIG. 2 is a bottom view of the liner;
FIG. 3 is a side view of the liner;
FIG. 4 is a rear view of the liner;
FIG. 5 is a front view of the liner; and,
FIG. 6 is a perspective view of the liner.
The drawings show only one side of the liner. The opposing side is identical to the one side shown in FIG. 3, except that the opposing side is the mirror image thereof.