Fixed a flicker when closing QS without notifications

Change-Id: I0ca13626a676d0adf427d95edd76dd1bd2228fdc
Fixes: 28008271
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/stack/NotificationStackScrollLayout.java b/packages/SystemUI/src/com/android/systemui/statusbar/stack/NotificationStackScrollLayout.java
index f67e285..6fd12914 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/stack/NotificationStackScrollLayout.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/stack/NotificationStackScrollLayout.java
@@ -2084,7 +2084,9 @@
         final ExpandableView firstChild = getFirstChildNotGone();
         int firstChildMinHeight = firstChild != null
                 ? firstChild.getIntrinsicHeight()
-                : mCollapsedSize;
+                : mEmptyShadeView != null
+                        ? mEmptyShadeView.getMinHeight()
+                        : mCollapsedSize;
         if (mOwnScrollY > 0) {
             firstChildMinHeight = Math.max(firstChildMinHeight - mOwnScrollY, mCollapsedSize);
         }