Fixed a bug where the scroller would stop tracking

Because we were not scrolling anymore in the QS area the shade
could become stuck and scrolled in too much.

Change-Id: I2c517d0a8da35230d0510c2a6b0e817d8d3567af
Fixes: 31440725

packages/SystemUI/src/com/android/systemui/statusbar/stack/NotificationStackScrollLayout.java

@@ -1228,7 +1228,7 @@ public class NotificationStackScrollLayout extends ViewGroup
         if (!isScrollingEnabled()) {
             return false;
         }
-        if (ev.getY() < mQsContainer.getBottom()) {
+        if (ev.getY() < mQsContainer.getBottom() && !mIsBeingDragged) {
             return false;
         }
         mForcedScroll = null;