[Sync] Add ability to save/restore Nigori to SyncEncryptionHandlerImpl

sync/sessions/model_type_registry.cc

Index: sync/sessions/model_type_registry.cc
diff --git a/sync/sessions/model_type_registry.cc b/sync/sessions/model_type_registry.cc
index 729727e0a73dabcc0a21521d65d67cec7252306b..0bd70b21b298d64a1a32529922e27e3763c21057 100644
--- a/sync/sessions/model_type_registry.cc
+++ b/sync/sessions/model_type_registry.cc
@@ -333,6 +333,10 @@ void ModelTypeRegistry::OnPassphraseTypeChanged(PassphraseType type,
                                                 base::Time passphrase_time) {
 }
 
+void ModelTypeRegistry::OnLocalSetPassphraseEncryption(
+    const SyncEncryptionHandler::NigoriState& nigori_state) {
+}
+
 ModelTypeSet ModelTypeRegistry::GetEnabledDirectoryTypes() const {
   return enabled_directory_types_;
 }