Pull out library needed for Notification CTS test.

Bug: 152031499
Test: atest NotificationManagerServiceTest
Change-Id: I6292482b3650709149ff06249ba4a3704289ee46
diff --git a/services/core/java/com/android/server/notification/NotificationRecordLogger.java b/services/core/java/com/android/server/notification/NotificationRecordLogger.java
index 6c833f9..eba5730 100644
--- a/services/core/java/com/android/server/notification/NotificationRecordLogger.java
+++ b/services/core/java/com/android/server/notification/NotificationRecordLogger.java
@@ -359,43 +359,24 @@
          * @return Small hash of the notification ID, and tag (if present).
          */
         int getNotificationIdHash() {
-            return smallHash(Objects.hashCode(r.getSbn().getTag()) ^ r.getSbn().getId());
+            return SmallHash.hash(Objects.hashCode(r.getSbn().getTag()) ^ r.getSbn().getId());
         }
 
         /**
          * @return Small hash of the channel ID, if present, or 0 otherwise.
          */
         int getChannelIdHash() {
-            return smallHash(r.getSbn().getNotification().getChannelId());
+            return SmallHash.hash(r.getSbn().getNotification().getChannelId());
         }
 
         /**
          * @return Small hash of the group ID, respecting group override if present. 0 otherwise.
          */
         int getGroupIdHash() {
-            return smallHash(r.getSbn().getGroup());
+            return SmallHash.hash(r.getSbn().getGroup());
         }
 
     }
 
-    // "Small" hashes will be in the range [0, MAX_HASH).
-    int MAX_HASH = (1 << 13);
-
-    /**
-     * Maps in to the range [0, MAX_HASH), keeping similar values distinct.
-     * @param in An arbitrary integer.
-     * @return in mod MAX_HASH, signs chosen to stay in the range [0, MAX_HASH).
-     */
-    static int smallHash(int in) {
-        return Math.floorMod(in, MAX_HASH);
-    }
-
-    /**
-     * @return Small hash of the string, if non-null, or 0 otherwise.
-     */
-    static int smallHash(@Nullable String in) {
-        return smallHash(Objects.hashCode(in));
-    }
-
 
 }