[Suggestions] Remove TreeNode.getSuggestionAt() in favor of a visitor.

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/AboveTheFoldItem.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.ntp.cards;
 
 /**
  * Item in the RecyclerView that will hold the above the fold contents for the NTP, i.e. the
  * logo, tiles and search bar that are initially visible when opening the NTP.
  *
  * When using the new NTP UI, that is based on a RecyclerView, the view containing the entire
  * content of the old UI is put in the AboveTheFoldItem, and inserted in the RecyclerView.
  * Other elements coming after it and initially off-screen are just added to the RecyclerView after
  * that.
  */
 class AboveTheFoldItem extends Leaf {
     @Override
     @ItemViewType
     protected int getItemViewType() {
         return ItemViewType.ABOVE_THE_FOLD;
     }
 
     @Override
     protected void onBindViewHolder(NewTabPageViewHolder holder) {
         // Nothing to do.
     }
+
+    @Override
+    public void visitItems(NodeVisitor visitor) {
+        visitor.visitAboveTheFoldItem();
+    }
 }