Validate context when using RS objects.

BUG=6035422

Change-Id: I8586be0085b36767289e1f634111c0ff076cec3c
diff --git a/graphics/java/android/renderscript/FieldPacker.java b/graphics/java/android/renderscript/FieldPacker.java
index 2739a4b8..a215a57 100644
--- a/graphics/java/android/renderscript/FieldPacker.java
+++ b/graphics/java/android/renderscript/FieldPacker.java
@@ -143,7 +143,7 @@
 
     public void addObj(BaseObj obj) {
         if (obj != null) {
-            addI32(obj.getID());
+            addI32(obj.getID(null));
         } else {
             addI32(0);
         }