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

sync/internal_api/sync_manager_impl.h

Index: sync/internal_api/sync_manager_impl.h
diff --git a/sync/internal_api/sync_manager_impl.h b/sync/internal_api/sync_manager_impl.h
index 283d3f11f57a48c9f6ec718730ffc277be313f41..07bc32fac1ece3eee5cdf9dc080c08adfd9a4ecc 100644
--- a/sync/internal_api/sync_manager_impl.h
+++ b/sync/internal_api/sync_manager_impl.h
@@ -123,6 +123,8 @@ class SYNC_EXPORT_PRIVATE SyncManagerImpl
   void OnCryptographerStateChanged(Cryptographer* cryptographer) override;
   void OnPassphraseTypeChanged(PassphraseType type,
                                base::Time explicit_passphrase_time) override;
+  void OnLocalSetCustomPassphrase(
+      const SyncEncryptionHandler::NigoriState& nigori_state) override;
 
   // SyncEngineEventListener implementation.
   void OnSyncCycleEvent(const SyncCycleEvent& event) override;