(1) On motion of the defendant or the counsel of the defendant, or on its own motion, the court shall dismiss any criminal proceeding not brought to trial in accordance with ORS 135.763.
(2) This section shall not apply:
(a) When failure to bring the adult in custody to trial within 90 days after the district attorney receives notice under ORS 135.760 was the result of motions filed on behalf of the adult in custody, or of a grant by the court of a continuance on motion of the district attorney or on its own motion, for good cause shown; or
(b) When the adult in custody is unavailable for trial, other than by imprisonment, or because of other pending criminal proceedings against the adult in custody.