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

chrome/android/java/src/org/chromium/chrome/browser/suggestions/TileGrid.java

 // Copyright 2017 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.suggestions;
 
 import android.view.LayoutInflater;
 import android.view.ViewGroup;
 
 import org.chromium.base.ContextUtils;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.ChromeFeatureList;
 import org.chromium.chrome.browser.ntp.ContextMenuManager;
 import org.chromium.chrome.browser.ntp.cards.ItemViewType;
 import org.chromium.chrome.browser.ntp.cards.NewTabPageViewHolder;
+import org.chromium.chrome.browser.ntp.cards.NodeVisitor;
 import org.chromium.chrome.browser.ntp.cards.OptionalLeaf;
 import org.chromium.chrome.browser.offlinepages.OfflinePageBridge;
 
 /**
  * The model and controller for a group of site suggestion tiles that will be rendered in a grid.
  */
 public class TileGrid extends OptionalLeaf implements TileGroup.Observer {
     /**
      * The maximum number of tiles to try and fit in a row. On smaller screens, there may not be
      * enough space to fit all of them.
@@ skipping 26 matching lines @@
         return ItemViewType.TILE_GRID;
     }
 
     @Override
     protected void onBindViewHolder(NewTabPageViewHolder holder) {
         assert holder instanceof ViewHolder;
         ((ViewHolder) holder).updateTiles(mTileGroup);
     }
 
     @Override
+    protected void visitOptionalItem(NodeVisitor visitor) {
+        visitor.visitTileGrid();
+    }
+
+    @Override
     public void onTileDataChanged() {
         setVisible(mTileGroup.getTiles().length != 0);
         if (isVisible()) notifyItemChanged(0, new ViewHolder.UpdateTilesCallback(mTileGroup));
     }
 
     @Override
     public void onTileCountChanged() {
         onTileDataChanged();
     }
 
@@ skipping 101 matching lines @@
             }
 
             @Override
             public void onResult(NewTabPageViewHolder holder) {
                 assert holder instanceof ViewHolder;
                 ((ViewHolder) holder).updateOfflineBadge(mTile);
             }
         }
     }
 }