gatekeeperd: use std::unique_ptr

std::unique_ptr is available in this scope. Substitute the UniquePtr to
std::unique_ptr.

Bug: 63686260
Test: build and boot
Merged-In: Ib8ea3fb5c49c0e92d962f65f1139b073168f8698
Change-Id: Ib8ea3fb5c49c0e92d962f65f1139b073168f8698
(cherry picked from commit 68b0ec6487186d59b1ec1dfcbc85673fc452bc4a)
diff --git a/gatekeeperd/SoftGateKeeperDevice.h b/gatekeeperd/SoftGateKeeperDevice.h
index 229f9a9..e3dc068 100644
--- a/gatekeeperd/SoftGateKeeperDevice.h
+++ b/gatekeeperd/SoftGateKeeperDevice.h
@@ -19,7 +19,7 @@
 
 #include "SoftGateKeeper.h"
 
-#include <nativehelper/UniquePtr.h>
+#include <memory>
 
 using namespace gatekeeper;
 
@@ -68,7 +68,7 @@
             const uint8_t *provided_password, uint32_t provided_password_length,
             uint8_t **auth_token, uint32_t *auth_token_length, bool *request_reenroll);
 private:
-    UniquePtr<SoftGateKeeper> impl_;
+    std::unique_ptr<SoftGateKeeper> impl_;
 };
 
 } // namespace gatekeeper