Update views when next slice is null

Otherwise invalid content would be presented after switching users

Test: manual, switch users, look at smart clock
Test: atest tests/src/com/android/keyguard/KeyguardSliceViewTest.java
Change-Id: Id3bd5e9cfedd17870d00f7a55386661f5b22ff59
Fixes: 78891765
diff --git a/packages/SystemUI/src/com/android/keyguard/KeyguardSliceView.java b/packages/SystemUI/src/com/android/keyguard/KeyguardSliceView.java
index c31cea2..ffe92fd 100644
--- a/packages/SystemUI/src/com/android/keyguard/KeyguardSliceView.java
+++ b/packages/SystemUI/src/com/android/keyguard/KeyguardSliceView.java
@@ -145,17 +145,13 @@
     }
 
     private void showSlice() {
-        if (mPulsing) {
+        if (mPulsing || mSlice == null) {
             mTitle.setVisibility(GONE);
             mRow.setVisibility(GONE);
             mContentChangeListener.accept(getLayoutTransition() != null);
             return;
         }
 
-        if (mSlice == null) {
-            return;
-        }
-
         ListContent lc = new ListContent(getContext(), mSlice);
         mHasHeader = lc.hasHeader();
         List<SliceItem> subItems = lc.getRowItems();