Pass the verify flag to DexFileLoader utilities.

Refactoring-only change.

Also remove unused DexFilerLoader::OpenMemory.

bug: 30972906
bug: 63920015

Test: build.

Change-Id: I7cd4b5787565ab1a3457ce2be6bb14657229c550
diff --git a/dex2oat/dex2oat_test.cc b/dex2oat/dex2oat_test.cc
index 1b731fc..dc1d54f 100644
--- a/dex2oat/dex2oat_test.cc
+++ b/dex2oat/dex2oat_test.cc
@@ -678,7 +678,8 @@
     const char* location = dex_location.c_str();
     std::string error_msg;
     std::vector<std::unique_ptr<const DexFile>> dex_files;
-    ASSERT_TRUE(DexFileLoader::Open(location, location, true, &error_msg, &dex_files));
+    ASSERT_TRUE(DexFileLoader::Open(
+        location, location, /* verify */ true, /* verify_checksum */ true, &error_msg, &dex_files));
     EXPECT_EQ(dex_files.size(), 1U);
     std::unique_ptr<const DexFile>& dex_file = dex_files[0];
     GenerateProfile(profile_location,
@@ -812,7 +813,8 @@
 
     const char* location = dex_location.c_str();
     std::vector<std::unique_ptr<const DexFile>> dex_files;
-    ASSERT_TRUE(DexFileLoader::Open(location, location, true, &error_msg, &dex_files));
+    ASSERT_TRUE(DexFileLoader::Open(
+        location, location, /* verify */ true, /* verify_checksum */ true, &error_msg, &dex_files));
     EXPECT_EQ(dex_files.size(), 1U);
     std::unique_ptr<const DexFile>& old_dex_file = dex_files[0];