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

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SuggestionsSection.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.support.annotation.CallSuper;
 import android.support.annotation.Nullable;
 
 import org.chromium.base.Callback;
@@ skipping 163 matching lines @@
             notifyItemRemoved(position);
             return suggestion;
         }
 
         @Override
         public Iterator<SnippetArticle> iterator() {
             return mSuggestions.iterator();
         }
 
         @Override
+        public void visitItems(NodeVisitor visitor) {
+            for (SnippetArticle suggestion : mSuggestions) {
+                visitor.visitSuggestion(suggestion);
+            }
+        }
+
+        @Override
         public Set<Integer> getItemDismissalGroup(int position) {
             return Collections.singleton(position);
         }
 
         @Override
         public void dismissItem(int position, Callback<String> itemRemovedCallback) {
             checkIndex(position);
             SuggestionsSource suggestionsSource = mUiDelegate.getSuggestionsSource();
             if (suggestionsSource == null) {
                 // It is possible for this method to be called after the NewTabPage has had
@@ skipping 340 matching lines @@
         public void onSuggestionOfflineIdChanged(SnippetArticle suggestion, @Nullable Long id) {
             mSuggestionsList.updateSuggestionOfflineId(suggestion, id);
         }
 
         @Override
         public Iterable<SnippetArticle> getOfflinableSuggestions() {
             return mSuggestionsList;
         }
     }
 }