Use unique_ptr to track ownership of dex files.

Bug: 18809837
Change-Id: Ie571eae8fc19ee9207390cff5c7e2a38071b126a
diff --git a/runtime/verifier/method_verifier_test.cc b/runtime/verifier/method_verifier_test.cc
index 770ca7e..f67adc1 100644
--- a/runtime/verifier/method_verifier_test.cc
+++ b/runtime/verifier/method_verifier_test.cc
@@ -41,14 +41,12 @@
         << error_msg;
   }
 
-  void VerifyDexFile(const DexFile* dex)
+  void VerifyDexFile(const DexFile& dex)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
-    ASSERT_TRUE(dex != NULL);
-
     // Verify all the classes defined in this file
-    for (size_t i = 0; i < dex->NumClassDefs(); i++) {
-      const DexFile::ClassDef& class_def = dex->GetClassDef(i);
-      const char* descriptor = dex->GetClassDescriptor(class_def);
+    for (size_t i = 0; i < dex.NumClassDefs(); i++) {
+      const DexFile::ClassDef& class_def = dex.GetClassDef(i);
+      const char* descriptor = dex.GetClassDescriptor(class_def);
       VerifyClass(descriptor);
     }
   }
@@ -56,7 +54,8 @@
 
 TEST_F(MethodVerifierTest, LibCore) {
   ScopedObjectAccess soa(Thread::Current());
-  VerifyDexFile(java_lang_dex_file_);
+  ASSERT_TRUE(java_lang_dex_file_ != nullptr);
+  VerifyDexFile(*java_lang_dex_file_);
 }
 
 }  // namespace verifier