Externalize test code

Change-Id: Iab19397c7a72fb9a3ca63bfd0bc4eaf1a98138ba
diff --git a/src/exception_test.cc b/src/exception_test.cc
index a1a101d..f2701dd 100644
--- a/src/exception_test.cc
+++ b/src/exception_test.cc
@@ -94,7 +94,7 @@
     return DexFile::CatchHandlerItem();
   }
 
-  scoped_ptr<DexFile> dex_;
+  scoped_ptr<const DexFile> dex_;
 
   Method* method_f_;
   Method* method_g_;