[Android NTP] Move suggestion sections into a separate node.

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ChildNode.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;
 
 /**
  * A node in the tree that has a parent and can notify it about changes.
  *
  * This class mostly serves as a convenience base class for implementations of {@link TreeNode}.
  */
 public abstract class ChildNode implements TreeNode {
     private final NodeParent mParent;
 
     protected ChildNode(NodeParent parent) {
         mParent = parent;
     }
 
+    @Override
+    public void init() {}
+
     protected void notifyItemRangeChanged(int index, int count) {
         mParent.onItemRangeChanged(this, index, count);
     }
 
     protected void notifyItemRangeInserted(int index, int count) {
         mParent.onItemRangeInserted(this, index, count);
     }
 
     protected void notifyItemRangeRemoved(int index, int count) {
         mParent.onItemRangeRemoved(this, index, count);
     }
 
     protected void notifyItemChanged(int index) {
         notifyItemRangeChanged(index, 1);
     }
 
     protected void notifyItemInserted(int index) {
         notifyItemRangeInserted(index, 1);
     }
 
     protected void notifyItemRemoved(int index) {
         notifyItemRangeRemoved(index, 1);
     }
 }