/**
   * Register a WebView to the current MaterialViewPagerAnimator Listen to
   * ObservableScrollViewCallbacks so give to $[observableScrollViewCallbacks] your
   * ObservableScrollViewCallbacks if you already use one For loadmore or anything else
   *
   * @param webView the scrollable
   * @param observableScrollViewCallbacks use it if you want to get a callback of the RecyclerView
   */
  public void registerWebView(
      final ObservableWebView webView,
      final ObservableScrollViewCallbacks observableScrollViewCallbacks) {
    if (webView != null) {
      if (scrollViewList.isEmpty()) onMaterialScrolled(webView, webView.getCurrentScrollY());
      scrollViewList.add(webView); // add to the scrollable list
      webView.setScrollViewCallbacks(
          new ObservableScrollViewCallbacks() {
            @Override
            public void onScrollChanged(int yOffset, boolean b, boolean b2) {
              if (observableScrollViewCallbacks != null)
                observableScrollViewCallbacks.onScrollChanged(yOffset, b, b2);

              if (isNewYOffset(yOffset)) onMaterialScrolled(webView, yOffset);
            }

            @Override
            public void onDownMotionEvent() {
              if (observableScrollViewCallbacks != null)
                observableScrollViewCallbacks.onDownMotionEvent();
            }

            @Override
            public void onUpOrCancelMotionEvent(ScrollState scrollState) {
              if (observableScrollViewCallbacks != null)
                observableScrollViewCallbacks.onUpOrCancelMotionEvent(scrollState);
            }
          });

      this.setScrollOffset(webView, -lastYOffset);
    }
  }
  public void onViewPagerPageChanged() {
    scrollDown(lastYOffset);

    View visibleView = getTheVisibileView(scrollViewList);
    if (!canScroll(visibleView)) {
      followScrollToolbarLayout(0);
      onMaterialScrolled(visibleView, 0);
    }
  }