[Android NTP] Move getDismissSiblingPosDelta into the TreeNode interface.

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SuggestionsSection.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SuggestionsSection.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SuggestionsSection.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SuggestionsSection.java
index ebad44ea6e30d2bf89d3dc9f47b0f2180b3a9760..9a4eaa2ab967de44516cbf5a09095fe4aad6c5a5 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SuggestionsSection.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/SuggestionsSection.java
@@ -36,7 +36,7 @@ public class SuggestionsSection extends InnerNode {
     }
 
     @Override
-    public List<TreeNode> getChildren() {
+    protected List<TreeNode> getChildren() {
         return mChildren;
     }
 
@@ -135,16 +135,7 @@ public class SuggestionsSection extends InnerNode {
         }
     }
 
-    /**
-     * The dismiss sibling is an item that should be dismissed at the same time as the provided
-     * one. For example, if we want to dismiss a status card that has a More button attached, the
-     * button is the card's dismiss sibling. This function return the adapter position delta to
-     * apply to get to the sibling from the provided item. For the previous example, it would return
-     * {@code +1}, as the button comes right after the status card.
-     *
-     * @return a position delta to apply to the position of the provided item to get the adapter
-     * position of the item to animate. Returns {@code 0} if there is no dismiss sibling.
-     */
+    @Override
     public int getDismissSiblingPosDelta(int position) {
         // The only dismiss siblings we have so far are the More button and the status card.
         // Exit early if there is no More button.
@@ -153,13 +144,13 @@ public class SuggestionsSection extends InnerNode {
         // When there are suggestions we won't have contiguous status and action items.
         if (hasSuggestions()) return 0;
 
-        TreeNode item = getChildren().get(position);
+        TreeNode child = getChildForPosition(position);
 
         // The sibling of the more button is the status card, that should be right above.
-        if (item == mMoreButton) return -1;
+        if (child == mMoreButton) return -1;
 
         // The sibling of the status card is the more button when it exists, should be right below.
-        if (item == mStatus) return 1;
+        if (child == mStatus) return 1;
 
         return 0;
     }