Introduced the visual stability manager

Notifications used to roam around and reorder whenever
they wished. Those little beasts must be tamed, hence
a new visual stability manager is introduced that
dictates the terms of their interplay.

Test: manual: add heads-up and see if they correctly appear
Test: runtest -x packages/SystemUI/tests/src/com/android/systemui/notification/VisualStabilityManagerTest.java
Bug: 32442500
Change-Id: I8d7596fa7c14e0df68459a77d445f618d517ad51
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
index a239cb6..7f6322a 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
@@ -63,6 +63,7 @@
 import com.android.systemui.statusbar.notification.NotificationUtils;
 import com.android.systemui.statusbar.policy.HeadsUpManager;
 import com.android.systemui.statusbar.policy.KeyguardUserSwitcher;
+import com.android.systemui.statusbar.policy.OnHeadsUpChangedListener;
 import com.android.systemui.statusbar.stack.NotificationStackScrollLayout;
 import com.android.systemui.statusbar.stack.StackStateAnimator;
 
@@ -72,7 +73,7 @@
         ExpandableView.OnHeightChangedListener,
         View.OnClickListener, NotificationStackScrollLayout.OnOverscrollTopChangedListener,
         KeyguardAffordanceHelper.Callback, NotificationStackScrollLayout.OnEmptySpaceClickListener,
-        HeadsUpManager.OnHeadsUpChangedListener, QS.HeightListener {
+        OnHeadsUpChangedListener, QS.HeightListener {
 
     private static final boolean DEBUG = false;