/usr/include/libsecret-1/libsecret/ is in libsecret-1-dev 0.18.5-3.1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libsecret-1/libsecret/secret-attributes.h
/usr/include/libsecret-1/libsecret/secret-collection.h
/usr/include/libsecret-1/libsecret/secret-enum-types.h
/usr/include/libsecret-1/libsecret/secret-item.h
/usr/include/libsecret-1/libsecret/secret-password.h
/usr/include/libsecret-1/libsecret/secret-paths.h
/usr/include/libsecret-1/libsecret/secret-prompt.h
/usr/include/libsecret-1/libsecret/secret-schema.h
/usr/include/libsecret-1/libsecret/secret-schemas.h
/usr/include/libsecret-1/libsecret/secret-service.h
/usr/include/libsecret-1/libsecret/secret-types.h
/usr/include/libsecret-1/libsecret/secret-value.h
/usr/include/libsecret-1/libsecret/secret.h