Unify NewTabPageItem and ItemGroup into a single tree-structured interface.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/AllDismissedItem.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/AllDismissedItem.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/AllDismissedItem.java
index 040a14cf651b8d1e3e1f265394abd6a4d6a6bac8..7d3991276a6e20f2f02043ac1e3c0e3d1eec7f02 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/AllDismissedItem.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/AllDismissedItem.java
@@ -22,10 +22,11 @@ import java.util.Calendar;
  * Displayed when all suggested content and their sections have been dismissed. Provides a button
  * to restore the dismissed sections and load new suggestions from the server.
  */
-public class AllDismissedItem extends SingleItemGroup {
+public class AllDismissedItem extends Leaf {
     @Override
-    public int getType() {
-        return NewTabPageItem.VIEW_TYPE_ALL_DISMISSED;
+    @ItemViewType
+    public int getItemViewType() {
+        return ItemViewType.VIEW_TYPE_ALL_DISMISSED;
     }
 
     @Override
@@ -35,7 +36,7 @@ public class AllDismissedItem extends SingleItemGroup {
     }
 
     /**
-     * ViewHolder for an item of type {@link #VIEW_TYPE_ALL_DISMISSED}.
+     * ViewHolder for an item of type {@link ItemViewType#VIEW_TYPE_ALL_DISMISSED}.
      */
     public static class ViewHolder extends NewTabPageViewHolder {
         private final TextView mBodyTextView;