NotificationStackScroller: Fix scrollTo for notification groups

Change-Id: Iab101d7583e9849809058c96f0c480ea9b5cc0f5
Fixes: 28936844
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/ExpandableNotificationRow.java b/packages/SystemUI/src/com/android/systemui/statusbar/ExpandableNotificationRow.java
index 6f6b02d..c2d8941 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/ExpandableNotificationRow.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/ExpandableNotificationRow.java
@@ -1486,6 +1486,13 @@
         updateBackground();
     }
 
+    public int getPositionOfChild(ExpandableNotificationRow childRow) {
+        if (mIsSummaryWithChildren) {
+            return mChildrenContainer.getPositionInLinearLayout(childRow);
+        }
+        return 0;
+    }
+
     public void setExpansionLogger(ExpansionLogger logger, String key) {
         mLogger = logger;
         mLoggingKey = key;