How do we review a trial court's decision to shackle a defendant under the abuse of standard?

We review a trial court's decision to shackle a defendant under an abuse of discretion standard. Spain v. Rushen, 883 F.2d 712, 716 (9th Cir.1989). But we review de novo the district court's ultimate decision to grant or deny a petition for habeas corpus. See id. Thus, we review de novo the district court's conclusion that the trial court did not abuse its discretion. Finally, we review for clear error any factual findings made by the district court in deciding the petition. Hayes v. Kincheloe, 784 F.2d 1434, 1436 (9th Cir.1986), cert. denied, 484 U.S. 871, 108 S.Ct. 198, 98 L.Ed.2d 150 (1987).