Make NumberInCallHistoryWorker class Private.

Test: TAP
PiperOrigin-RevId: 163911841
Change-Id: I454a649e8e31e744de99c2d9599f5bf291c729f1
diff --git a/java/com/android/incallui/spam/SpamCallListListener.java b/java/com/android/incallui/spam/SpamCallListListener.java
index 27e58a7..7ca3fbb 100644
--- a/java/com/android/incallui/spam/SpamCallListListener.java
+++ b/java/com/android/incallui/spam/SpamCallListListener.java
@@ -82,7 +82,7 @@
 
   /** Checks if the number is in the call history. */
   @TargetApi(VERSION_CODES.M)
-  static final class NumberInCallHistoryWorker implements Worker<Void, Integer> {
+  private final class NumberInCallHistoryWorker implements Worker<Void, Integer> {
 
     private final Context appContext;
     private final String number;