LOS ANGELES — The son of Robert Downey Jr. pleaded guilty on Friday to cocaine possession and was sentenced to a drug diversion program that could result in his conviction being dismissed.

As the actor watched in the courtroom, Indio Downey, 21, thanked Superior Court Judge Keith L. Schwartz for allowing him to enter the program and pledged to take the advice of the judge to heed the lessons of treatment and get advice from his father if necessary.

“I appreciate this opportunity and I intend to make the most of it,” he told the judge.