The ornamental design for a chest brace, as shown and described.
FIG. 1 is a left side, front and top perspective view of a chest brace showing my new design;
FIG. 2 is a back, top and right side perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a back view thereof;
FIG. 5 is a left view thereof;
FIG. 6 is a right view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The broken lines in the drawings and the unshaded areas within the broken lines are for the purpose of illustrating portions of the chest brace that form no part of the claim.