While I didn't know you could ever take practice putts in medal play, only local rule or PGA prohibits... I still haven't seen an answer for practice chips in match play.
What if a guy in the upcoming President's cup rather than practice putts after his group has holed out, drops a ball in rough 5 feet off of a green because he may have chili dipped one, and practices that?
From the USGA Rules of Golf:
7-2 During Round
A player must not make a practice stroke during play of a hole.
Between the play of two holes, a player must not make a practice stroke, except that he may practice putting or chipping on or near:
(a) the putting green of the hole last played, (b) any practice putting green, or (c) the teeing ground of the next hole to be played in the round,provided a practice stroke is not made from a hazard and does not unduly delay play (Rule 6-7).
Strokes made in continuing the play of a hole, the result of which has been decided, are not practice strokes.
Exception: When play has been suspended by the Committee, a player may, prior to resumption of play, practice (a) as provided in this Rule, (b) anywhere other than on the competition course and (c) as otherwise permitted by the Committee.
Penalty for Breach of Rule 7-2:
Match play — Loss of hole; Stroke play— Two strokes.
In the event of a breach between the play of two holes, the penalty applies to the next hole.
Note 1: A practice swing is not a practice stroke and may be taken at any place, provided the player does not breach the Rules,.
Note 2: The Committee may, in the conditions of a competition (Rule 33-1), prohibit:
(a) practice on or near the putting green of the hole last played, and(b) rolling a ball on the putting green of the hole last played.
Of course this begs the question - When is "chipping", no longer "chipping"? The Rules of Golf do not define chipping, and none of the decisions I saw answer this question.