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

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

Index: chrome/android/java/src/org/chromium/chrome/browser/suggestions/TileGrid.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/suggestions/TileGrid.java b/chrome/android/java/src/org/chromium/chrome/browser/suggestions/TileGrid.java
index d82f31335f8e2808bbd4f145a6e1d30d88228599..b4cb9396d8766ece5297bc0eba4b17f4a1595e9c 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/suggestions/TileGrid.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/suggestions/TileGrid.java
@@ -13,6 +13,7 @@ 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;
 
@@ -59,6 +60,11 @@ public class TileGrid extends OptionalLeaf implements TileGroup.Observer {
     }
 
     @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));