Messaging: Further code improvements

* Remove redundant casts
* getParcelable(ArrayList|Exra) without class argument is deprecated
* ViewPager.setOnPageChangeListener -> addOnPageChangeListener
* RecyclerView.setOnScrollListener -> addOnScrollListener
* Remove unused initializations
* Remove unused code

Change-Id: I21beb6c90c675a4f2cfd7e3d5ebbd18b745f5911

src/com/android/messaging/datamodel/MessagingContentProvider.java

@@ -446,7 +446,7 @@ public class MessagingContentProvider extends ContentProvider {
     @Override
     public boolean onCreate() {
         // This is going to wind up calling into createDatabase() below.
-        mDatabaseHelper = (DatabaseHelper) getDatabase();
+        mDatabaseHelper = getDatabase();
         // We cannot initialize mDatabaseWrapper yet as the Factory may not be initialized
         return true;
     }