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

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SpacingItem.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;
 
 import android.content.Context;
 import android.view.View;
 import android.view.ViewGroup;
 
@@ skipping 24 matching lines @@
     @ItemViewType
     protected int getItemViewType() {
         return ItemViewType.SPACING;
     }
 
     @Override
     protected void onBindViewHolder(NewTabPageViewHolder holder) {
         // Nothing to do.
     }
 
+    @Override
+    public void visitItems(NodeVisitor visitor) {
+        visitor.visitSpacingItem();
+    }
+
     /** Schedules a recalculation of the space occupied by the item. */
     public void refresh() {
         notifyItemChanged(0);
     }
 }