NTP cards: Restructure change notifications.

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 5193a69c97cc36470bb4f48ef95acacd1600eecf..b2698908e218ccc2605ea663b9f0d9b6e0926fa5 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
@@ -20,13 +20,13 @@ public interface ItemGroup {
      * an {@link ItemGroup}.
      */
     interface Observer {
-        /** Non specific notification about changes inside of the group. */
-        void notifyGroupChanged(ItemGroup group, int itemCountBefore, int itemCountAfter);
+        /** Notification about items having been changed in the group. */
+        void onItemRangeChanged(ItemGroup group, int itemPosition, int itemCount);
 
-        /** Notification about an item having been added to the group. */
-        void notifyItemInserted(ItemGroup group, int itemPosition);
+        /** Notification about items having been added to the group. */
+        void onItemRangeInserted(ItemGroup group, int itemPosition, int itemCount);
 
-        /** Notification about an item having been removed from the group. */
-        void notifyItemRemoved(ItemGroup group, int itemPosition);
+        /** Notification about items having been removed from the group. */
+        void onItemRangeRemoved(ItemGroup group, int itemPosition, int itemCount);
     }
 }