Cros: Use transforms for navigation widget bounds animator

Bug: 1049705
Change-Id: I70e9dbd7a312bbd2f0418733d14ab0857db0e432
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2086257Reviewed-by: Manu Cornet <manucornet@chromium.org>
Commit-Queue: Ana Salazar <anasalazar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#746875}

ash/shelf/shelf_navigation_widget.cc

@@ -400,7 +400,9 @@ ShelfNavigationWidget::ShelfNavigationWidget(Shelf* shelf,
                                              ShelfView* shelf_view)
     : shelf_(shelf),
       delegate_(new ShelfNavigationWidget::Delegate(shelf, shelf_view)),
-      bounds_animator_(std::make_unique<views::BoundsAnimator>(delegate_)),
+      bounds_animator_(
+          std::make_unique<views::BoundsAnimator>(delegate_,
+                                                  /*use_transforms=*/true)),
       back_button_metrics_reporter_(
           std::make_unique<NavigationButtonAnimationMetricsReporter>(
               shelf,