Clean up interfaces for StackScrollLayout.

Test: Automated tests should pass.
Change-Id: Ibf2718bfaacff0adcfca7ef8ca2f3eb2b867debf
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 6d53cd3..7507702 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java
@@ -2521,8 +2521,8 @@
     @Override
     public void setHeadsUpManager(HeadsUpManagerPhone headsUpManager) {
         super.setHeadsUpManager(headsUpManager);
-        mHeadsUpTouchHelper = new HeadsUpTouchHelper(headsUpManager, mNotificationStackScroller,
-                this);
+        mHeadsUpTouchHelper = new HeadsUpTouchHelper(headsUpManager,
+                mNotificationStackScroller.getHeadsUpCallback(), this);
     }
 
     public void setTrackedHeadsUp(ExpandableNotificationRow pickedChild) {