Placeholder API for encrypted storage

Add a method to retrieve the path to encrypted storage. For now,
always return null, as there isn't any.

Bug: 254454578
Bug: 243512108
Test: atest MicrodroidTests
Change-Id: I87868e878dcbc0f2d13870024efbaafb0b52d7e3
diff --git a/tests/testapk/src/native/testbinary.cpp b/tests/testapk/src/native/testbinary.cpp
index 48942dc..694f452 100644
--- a/tests/testapk/src/native/testbinary.cpp
+++ b/tests/testapk/src/native/testbinary.cpp
@@ -123,6 +123,16 @@
             *out = path;
             return ndk::ScopedAStatus::ok();
         }
+
+        ndk::ScopedAStatus getEncryptedStoragePath(std::string* out) override {
+            const char* path_c = AVmPayload_getEncryptedStoragePath();
+            if (path_c == nullptr) {
+                out->clear();
+            } else {
+                *out = path_c;
+            }
+            return ndk::ScopedAStatus::ok();
+        }
     };
     auto testService = ndk::SharedRefBase::make<TestService>();