Merge "[4/n] Add Apply Button to grid preview page" into udc-qpr-dev am: 8e191fd9a1 am: 210d17c227

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/24435476

Change-Id: I43715e218a5e7c05136cecb8589be0ea050ebb86
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>