Using singleton OSInAppMessageController.java instead of new

* Created singleton based `getInAppMessageRepository` method inside of `OSInAppMessageController.java` class
* This allows the synchronized to apply to multiple methods being called from the class instance
* Deleted unused thread name since new Thread was moved toi cache cleaning file with different thread name now

Author: mikechoch

OneSignalSDK/onesignal/src/main/java/com/onesignal/OSInAppMessageController.java

@@ -32,7 +32,6 @@ class OSInAppMessageController implements OSDynamicTriggerControllerObserver, OS
 
     public static final String IN_APP_MESSAGES_JSON_KEY = "in_app_messages";
     private static final String OS_SAVE_IN_APP_MESSAGE = "OS_SAVE_IN_APP_MESSAGE";
-    private static final String OS_DELETE_IN_APP_MESSAGE = "OS_DELETE_IN_APP_MESSAGE";
 
     OSTriggerController triggerController;
     private OSSystemConditionController systemConditionController;
@@ -122,8 +121,15 @@ protected OSInAppMessageController(OneSignalDbHelper dbHelper) {
         initRedisplayData(dbHelper);
     }
 
+    OSInAppMessageRepository getInAppMessageRepository(OneSignalDbHelper dbHelper) {
+        if (inAppMessageRepository == null)
+            inAppMessageRepository = new OSInAppMessageRepository(dbHelper);
+
+        return inAppMessageRepository;
+    }
+
     protected void initRedisplayData(OneSignalDbHelper dbHelper) {
-        inAppMessageRepository = new OSInAppMessageRepository(dbHelper);
+        inAppMessageRepository = getInAppMessageRepository(dbHelper);
         redisplayedInAppMessages = inAppMessageRepository.getCachedInAppMessages();
 
         OneSignal.Log(OneSignal.LOG_LEVEL.DEBUG, "redisplayedInAppMessages: " + redisplayedInAppMessages.toString());

OneSignalSDK/onesignal/src/main/java/com/onesignal/OneSignalCacheCleaner.java

@@ -71,7 +71,11 @@ synchronized static void cleanCachedInAppMessages(final OneSignalDbHelper dbHelp
             @Override
             public void run() {
                 Thread.currentThread().setPriority(Process.THREAD_PRIORITY_BACKGROUND);
-                new OSInAppMessageRepository(dbHelper).cleanCachedInAppMessages();
+
+                OSInAppMessageRepository inAppMessageRepository = OSInAppMessageController
+                        .getController()
+                        .getInAppMessageRepository(dbHelper);
+                inAppMessageRepository.cleanCachedInAppMessages();
             }
         }, OS_DELETE_CACHED_REDISPLAYED_IAMS_THREAD).start();
     }