[Android NTP] Move suggestions in SuggestionSection into a separate TreeNode.

chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticle.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.snippets;
 
 import android.graphics.Bitmap;
 
-import org.chromium.chrome.browser.ntp.cards.ItemViewType;
-import org.chromium.chrome.browser.ntp.cards.Leaf;
-import org.chromium.chrome.browser.ntp.cards.NewTabPageViewHolder;
 import org.chromium.chrome.browser.ntp.snippets.ContentSuggestionsCardLayout.ContentSuggestionsCardLayoutEnum;
 
 /**
  * Represents the data for an article card on the NTP.
  */
-public class SnippetArticle extends Leaf {
+public class SnippetArticle {
     /** The category of this article. */
     public final int mCategory;
 
     /** The identifier for this article within the category - not necessarily unique globally. */
     public final String mIdWithinCategory;
 
     /** The title of this article. */
     public final String mTitle;
 
     /** The canonical publisher name (e.g., New York Times). */
@@ skipping 54 matching lines @@
         if (!(other instanceof SnippetArticle)) return false;
         SnippetArticle rhs = (SnippetArticle) other;
         return mCategory == rhs.mCategory && mIdWithinCategory.equals(rhs.mIdWithinCategory);
     }
 
     @Override
     public int hashCode() {
         return mCategory ^ mIdWithinCategory.hashCode();
     }
 
-    @Override
-    @ItemViewType
-    public int getItemViewType() {
-        return ItemViewType.SNIPPET;
-    }
-
-    @Override
-    protected void onBindViewHolder(NewTabPageViewHolder holder) {
-        assert holder instanceof SnippetArticleViewHolder;
-        ((SnippetArticleViewHolder) holder).onBindViewHolder(this);
-    }
-
-    @Override
-    public SnippetArticle getSuggestionAt(int position) {
-        if (position != 0) throw new IndexOutOfBoundsException();
-
-        return this;
-    }
-
     /**
      * Returns this article's thumbnail as a {@link Bitmap}. Can return {@code null} as it is
      * initially unset.
      */
     public Bitmap getThumbnailBitmap() {
         return mThumbnailBitmap;
     }
 
     /** Sets the thumbnail bitmap for this article. */
     public void setThumbnailBitmap(Bitmap bitmap) {
         mThumbnailBitmap = bitmap;
     }
 
     /** Returns whether to track an impression for this article. */
     public boolean trackImpression() {
         // Track UMA only upon the first impression per life-time of this object.
         if (mImpressionTracked) return false;
         mImpressionTracked = true;
         return true;
     }
 
     @Override
     public String toString() {
         // For debugging purposes. Displays the first 42 characters of the title.
         return String.format("{%s, %1.42s}", getClass().getSimpleName(), mTitle);
     }
 }