Refactor to use EncryptionPolicy everywhere we used to use raw_ref

Test: Boots, no bad log messages: Cuttlefish with v2 policies, Taimen
Bug: 147733587
Change-Id: Ice4acac3236b6b7d90e60a2f57b46814aa1949f5
diff --git a/MetadataCrypt.cpp b/MetadataCrypt.cpp
index 3c2e0d5..c621823 100644
--- a/MetadataCrypt.cpp
+++ b/MetadataCrypt.cpp
@@ -135,7 +135,9 @@
             unlink(newKeyPath.c_str());
     }
     bool needs_cp = cp_needsCheckpoint();
-    if (!android::vold::retrieveKey(create_if_absent, dir, temp, key, needs_cp)) return false;
+    if (!android::vold::retrieveKey(create_if_absent, kEmptyAuthentication, dir, temp, key,
+                                    needs_cp))
+        return false;
     if (needs_cp && pathExists(newKeyPath)) std::thread(commit_key, dir).detach();
     return true;
 }