Test that plaintext can't be read from disk for encrypted files.

Bug: 36029169
Test: tested by hand on Taimen
Change-Id: I5717a8630bb2c8d8fe5c343d519c4e59862ecbdf
diff --git a/VoldNativeService.h b/VoldNativeService.h
index 8368bdc..7ca72e5 100644
--- a/VoldNativeService.h
+++ b/VoldNativeService.h
@@ -51,6 +51,7 @@
     binder::Status format(const std::string& volId, const std::string& fsType);
     binder::Status benchmark(const std::string& volId,
             const android::sp<android::os::IVoldTaskListener>& listener);
+    binder::Status checkEncryption(const std::string& volId);
 
     binder::Status moveStorage(const std::string& fromVolId, const std::string& toVolId,
             const android::sp<android::os::IVoldTaskListener>& listener);