Adding a rank column for itemInfo

> Rank is used to determine position of an item
in a folder.

Bug: 18590192
Change-Id: I2826a7c570b4cc58e719d685f17a24ec6133804f
diff --git a/src/com/android/launcher3/Utilities.java b/src/com/android/launcher3/Utilities.java
index 215d63d..1a9b9a1 100644
--- a/src/com/android/launcher3/Utilities.java
+++ b/src/com/android/launcher3/Utilities.java
@@ -49,6 +49,7 @@
 import android.widget.Toast;
 
 import java.util.ArrayList;
+import java.util.Comparator;
 
 /**
  * Various utilities shared amongst the Launcher's classes.
@@ -542,4 +543,12 @@
         }
         return defaultWidgetForSearchPackage;
     }
+
+    public static final Comparator<ItemInfo> RANK_COMPARATOR = new Comparator<ItemInfo>() {
+
+        @Override
+        public int compare(ItemInfo lhs, ItemInfo rhs) {
+            return lhs.rank - rhs.rank;
+        }
+    };
 }