[Android NTP] Cache number of items under child nodes

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

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/Leaf.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/Leaf.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/Leaf.java
index 1df0a871d41b1a9155122001a70d141819e42fe0..8ba3e9a05a180483444b1d1cfdaa8e08a3eae344 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/Leaf.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/Leaf.java
@@ -16,8 +16,14 @@ import java.util.Set;
  * implementation that will take care of hiding or showing the item.
  */
 public abstract class Leaf extends ChildNode {
+    protected Leaf() {
+        // Initialize the item count to 1 (at this point the parent is null, so no notification will
+        // be sent).
+        notifyItemInserted(0);
+    }
+
     @Override
-    public int getItemCount() {
+    protected final int getItemCountForDebugging() {
         return 1;
     }