Abort sync cycles when download step fails

sync/sessions/sync_session.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sync/sessions/sync_session.h"
 
 #include <algorithm>
 #include <iterator>
 
 #include "base/logging.h"
@@ skipping 216 matching lines @@
 
   return enabled_groups_with_verified_updates;
 }
 
 namespace {
 // Return true if the command in question was attempted and did not complete
 // successfully.
 //
 bool IsError(SyncerError error) {
   return error != UNSET
-      && error != SYNCER_OK
-      && error != SERVER_RETURN_MIGRATION_DONE;
+      && error != SYNCER_OK;
 }
 }  // namespace
 
 bool SyncSession::Succeeded() const {
   const bool download_updates_error =
       IsError(status_controller_->error().last_download_updates_result);
   const bool post_commit_error =
       IsError(status_controller_->error().last_post_commit_result);
   const bool process_commit_response_error =
       IsError(status_controller_->error().last_process_commit_response_result);
   return !download_updates_error
       && !post_commit_error
       && !process_commit_response_error;
 }
 
 }  // namespace sessions
 }  // namespace browser_sync