@Override
    public boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow) {
        return mChildHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow);
    }
Sentinel value for no current active pointer.
Used by {@link #mActivePointerId}.
app/src/main/java/home/smart/fly/animations/widget/NestedScrollView.java