Reuse SIRT for C++ references

Change-Id: I8310e55da42f55f7ec60f6b17face436c77a979f
diff --git a/src/dex_cache_test.cc b/src/dex_cache_test.cc
index 25f194a..054f991 100644
--- a/src/dex_cache_test.cc
+++ b/src/dex_cache_test.cc
@@ -13,8 +13,8 @@
 class DexCacheTest : public CommonTest {};
 
 TEST_F(DexCacheTest, Open) {
-  DexCache* dex_cache = class_linker_->AllocDexCache(*java_lang_dex_file_.get());
-  ASSERT_TRUE(dex_cache != NULL);
+  SirtRef<DexCache> dex_cache(class_linker_->AllocDexCache(*java_lang_dex_file_.get()));
+  ASSERT_TRUE(dex_cache.get() != NULL);
 
   EXPECT_EQ(java_lang_dex_file_->NumStringIds(), dex_cache->NumStrings());
   EXPECT_EQ(java_lang_dex_file_->NumTypeIds(),   dex_cache->NumResolvedTypes());