sync: Add non-blocking type encryption support

sync/util/cryptographer.cc

Index: sync/util/cryptographer.cc
diff --git a/sync/util/cryptographer.cc b/sync/util/cryptographer.cc
index 29f378125a728bf9adb4ff0cae1e51556952f385..8c71e12f03cda8cac44db6dfc956422c12beb7bd 100644
--- a/sync/util/cryptographer.cc
+++ b/sync/util/cryptographer.cc
@@ -324,6 +324,10 @@ bool Cryptographer::KeybagIsStale(
   return false;
 }
 
+std::string Cryptographer::GetDefaultKeyName() const {
+  return default_nigori_name_;
+}
+
 std::string Cryptographer::GetDefaultNigoriKey() const {
   if (!is_initialized())
     return std::string();