Add a ClientAction used by SyncRollbackManager to notify PSS that rollback is

chrome/browser/sync/test/integration/sync_test.cc

Index: chrome/browser/sync/test/integration/sync_test.cc
diff --git a/chrome/browser/sync/test/integration/sync_test.cc b/chrome/browser/sync/test/integration/sync_test.cc
index 91adcf69cc9ec8aea344f467457e28cf74f14788..2cd83b1332503dc3838e52a40277270cc9b20f39 100644
--- a/chrome/browser/sync/test/integration/sync_test.cc
+++ b/chrome/browser/sync/test/integration/sync_test.cc
@@ -976,6 +976,7 @@ sync_pb::SyncEnums::Action GetClientToServerResponseAction(
       return sync_pb::SyncEnums::DISABLE_SYNC_ON_CLIENT;
     case syncer::STOP_SYNC_FOR_DISABLED_ACCOUNT:
     case syncer::DISABLE_SYNC_AND_ROLLBACK:
+    case syncer::ROLLBACK_DONE:
       NOTREACHED();   // No corresponding proto action for these. Shouldn't
                       // test.
       return sync_pb::SyncEnums::UNKNOWN_ACTION;