Merge "Use the LayoutManager as the source of truth for visible positions" into sc-dev am: 5cc44eb73e am: 3256647b03 am: be3698c944

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/14800536

Change-Id: Ifc3f95f40eea42e5e6a3dcb5d2d8afe3eae04159