Properly handle initialization failure and following manager shutdown without

sync/internal_api/sync_rollback_manager.cc

Index: sync/internal_api/sync_rollback_manager.cc
diff --git a/sync/internal_api/sync_rollback_manager.cc b/sync/internal_api/sync_rollback_manager.cc
index 84367b082b05de7e085b09c50c696c68d4935966..9a54f039d8b627e8deac99d44f3e573a4531a15a 100644
--- a/sync/internal_api/sync_rollback_manager.cc
+++ b/sync/internal_api/sync_rollback_manager.cc
@@ -53,6 +53,9 @@ void SyncRollbackManager::Init(
                                 report_unrecoverable_error_function,
                                 cancelation_signal);
 
+  if (!initialized())
+    return;
+
   change_delegate_ = change_delegate;
 
   for (size_t i = 0; i < workers.size(); ++i) {