Merge "Remove PreviewFragment (2/3)" into udc-qpr-dev am: 8d49225c18 am: 2798c86420

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/24526538

Change-Id: Ide2bd2c0bffabd704ebb6fbed7c94ffb7040536d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>