Merge "Re-add dividers when expanding notifications." into sc-dev am:...

Merge "Re-add dividers when expanding notifications." into sc-dev am: e6b421ae am: fbfd76f7 am: 133a642b

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15017662

Change-Id: I096365dd2a74c41621e37b89c46ba57e77139bec