public void setAssociatedScrollView(ContentScrollView scrollView) {
        this.mScrollView = scrollView;
        this.mScrollView.setScrollbarFadingEnabled(false);
        this.mScrollView.setOnScrollChangeListener(mOnScrollChangedListener);
    }
Set associated list view, then this layout will only be able to drag down when the list
view is scrolled to top.

@param recyclerView
scrolllayout/src/main/java/com/yinglan/scrolllayout/ScrollLayout.java