📰 Stop refreshing the whole NTP for every adapter change

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

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ItemGroup.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ItemGroup.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ItemGroup.java
index db393a71b77ad41be1e84945430e470d113c5489..5193a69c97cc36470bb4f48ef95acacd1600eecf 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ItemGroup.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/ItemGroup.java
@@ -14,4 +14,19 @@
      * @return A list of items contained in this group. The list should not be modified.
      */
     List<NewTabPageItem> getItems();
+
+    /**
+     * Defines the actions an object can be notified about when there are changes inside of
+     * an {@link ItemGroup}.
+     */
+    interface Observer {
+        /** Non specific notification about changes inside of the group. */
+        void notifyGroupChanged(ItemGroup group, int itemCountBefore, int itemCountAfter);
+
+        /** Notification about an item having been added to the group. */
+        void notifyItemInserted(ItemGroup group, int itemPosition);
+
+        /** Notification about an item having been removed from the group. */
+        void notifyItemRemoved(ItemGroup group, int itemPosition);
+    }
 }