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/data/MessageData.java

@@ -837,7 +837,8 @@ public class MessageData implements Parcelable {
         mParts = new ArrayList<>();
         final int partCount = in.readInt();
         for (int i = 0; i < partCount; i++) {
-            mParts.add((MessagePartData) in.readParcelable(MessagePartData.class.getClassLoader()));
+            mParts.add(in.readParcelable(MessagePartData.class.getClassLoader(),
+                    MessagePartData.class));
         }
     }