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

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/NewTabPageAdapter.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.Nullable;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.RecyclerView.Adapter;
 import android.view.View;
 import android.view.ViewGroup;
 
 import org.chromium.base.Callback;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.browser.ChromeFeatureList;
 import org.chromium.chrome.browser.ntp.ContextMenuManager;
 import org.chromium.chrome.browser.ntp.cards.NewTabPageViewHolder.PartialBindCallback;
 import org.chromium.chrome.browser.ntp.snippets.SectionHeaderViewHolder;
-import org.chromium.chrome.browser.ntp.snippets.SnippetArticle;
 import org.chromium.chrome.browser.ntp.snippets.SnippetArticleViewHolder;
 import org.chromium.chrome.browser.offlinepages.OfflinePageBridge;
 import org.chromium.chrome.browser.suggestions.SuggestionsRecyclerView;
 import org.chromium.chrome.browser.suggestions.SuggestionsUiDelegate;
 import org.chromium.chrome.browser.suggestions.TileGrid;
 import org.chromium.chrome.browser.suggestions.TileGroup;
 import org.chromium.chrome.browser.widget.displaystyle.UiConfig;
 
 import java.util.List;
 import java.util.Set;
@@ skipping 255 matching lines @@
 
     private boolean hasAllBeenDismissed() {
         return mSections.isEmpty() && !mSigninPromo.isVisible();
     }
 
     private int getChildPositionOffset(TreeNode child) {
         return mRoot.getStartingOffsetForChild(child);
     }
 
     @VisibleForTesting
-    SnippetArticle getSuggestionAt(int position) {
-        return mRoot.getSuggestionAt(position);
-    }
-
-    @VisibleForTesting
     int getFirstPositionForType(@ItemViewType int viewType) {
         int count = getItemCount();
         for (int i = 0; i < count; i++) {
             if (getItemViewType(i) == viewType) return i;
         }
         return RecyclerView.NO_POSITION;
     }
 
     SectionList getSectionListForTesting() {
         return mSections;
     }
 
     InnerNode getRootForTesting() {
         return mRoot;
     }
 }