Remove opening of DexFile from pointer

Change-Id: I158e75e9e72f1dcc579742ff08c80d3f857852b3
diff --git a/src/dex_file_test.cc b/src/dex_file_test.cc
index 3a9b6f4..ad3b17b 100644
--- a/src/dex_file_test.cc
+++ b/src/dex_file_test.cc
@@ -41,7 +41,8 @@
   "AAMgAAACAAAAiAIAAAQgAAADAAAAlAIAAAAgAAACAAAAqwIAAAAQAAABAAAAxAIAAA==";
 
 TEST_F(DexFileTest, Header) {
-  UniquePtr<const DexFile> raw(OpenDexFileBase64(kRawDex, "kRawDex"));
+  ScratchFile tmp;
+  UniquePtr<const DexFile> raw(OpenDexFileBase64(kRawDex, tmp.GetFilename()));
   ASSERT_TRUE(raw.get() != NULL);
 
   const DexFile::Header& header = raw->GetHeader();