Merge "Notification footer shows when there are zero notifications" into sc-dev am: 5b0cad99 am: 978426cd am: fd695493

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15095468

Change-Id: Idcb8abcf74a9625d77e66219b75341d9c1c62227