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

sync/internal_api/js_sync_encryption_handler_observer.cc

Index: sync/internal_api/js_sync_encryption_handler_observer.cc
diff --git a/sync/internal_api/js_sync_encryption_handler_observer.cc b/sync/internal_api/js_sync_encryption_handler_observer.cc
index a000fa674f31ea3a0f8b7e3ce4efaa90878c11aa..7924d31f283a4877988aacd1b602914e7135b1fe 100644
--- a/sync/internal_api/js_sync_encryption_handler_observer.cc
+++ b/sync/internal_api/js_sync_encryption_handler_observer.cc
@@ -113,6 +113,10 @@ void JsSyncEncryptionHandlerObserver::OnPassphraseTypeChanged(
                 JsEventDetails(&details));
 }
 
+void JsSyncEncryptionHandlerObserver::OnLocalSetPassphraseEncryption(
+    const SyncEncryptionHandler::NigoriState& nigori_state) {
+}
+
 void JsSyncEncryptionHandlerObserver::HandleJsEvent(
     const tracked_objects::Location& from_here,
     const std::string& name, const JsEventDetails& details) {