Don't intercept touches when the qs scrollview can't scroll

This could lead to users not being able to collapse.

Fixes: 159420191
Test: expand qs, try to collapse from the 3 dot region
Change-Id: Iaa19e607919615777e5b21bbbd6325b6794b710a

packages/SystemUI/src/com/android/systemui/qs/NonInterceptingScrollView.java

@@ -46,6 +46,11 @@ public class NonInterceptingScrollView extends ScrollView {
                     if (parent != null) {
                         parent.requestDisallowInterceptTouchEvent(true);
                     }
+                } else if (!canScrollVertically(-1)) {
+                    // Don't pass on the touch to the view, because scrolling will unconditionally
+                    // disallow interception even if we can't scroll.
+                    // if a user can't scroll at all, we should never listen to the touch.
+                    return false;
                 }
                 break;
         }