Merge "Uses WorkspaceSurfaceHolderCallback for GridPreviewer" into ub-launcher3-master am: b534562d45 am: 276abf8fa5

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/ThemePicker/+/11747783

Change-Id: I88285dfaee6035d983ffeb0ae72a341572b61f24