Fix a crash where the deletion helper crashes when app sizes load.

This was caused by a change I made to the extraInfo on the app.
The extra info used to be a long which was the last usage time.
I changed it to a UsageStatsState and missed this usage of it.
The attempted cast to long caused a crash.

Bug: 28885317
Change-Id: Ie0d6bcea5d0afccd2762acd19d628c742c7e3db9

src/com/android/settings/deletionhelper/AppStateUsageStatsBridge.java

@@ -137,7 +137,10 @@ public class AppStateUsageStatsBridge extends AppStateBaseBridge {
         }
     };
 
-    private class UsageStatsState {
+    /**
+     * UsageStatsState contains the days since the last use and first install of a given app.
+     */
+    public static class UsageStatsState {
         public long daysSinceLastUse;
         public long daysSinceFirstInstall;