Sync: Support multiple setup UIs.

components/sync_driver/sync_service.cc

 // Copyright 2015 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 "components/sync_driver/sync_service.h"
 
 #include "google_apis/gaia/google_service_auth_error.h"
 #include "sync/internal_api/public/sync_manager.h"
 
 namespace sync_driver {
 
+SyncSetupInProgressHandle::SyncSetupInProgressHandle(base::Closure on_destroy)
+    : on_destroy_(on_destroy) {}
+
+SyncSetupInProgressHandle::~SyncSetupInProgressHandle() {
+  on_destroy_.Run();
+}
+
 SyncService::SyncTokenStatus::SyncTokenStatus()
     : connection_status(syncer::CONNECTION_NOT_ATTEMPTED),
       last_get_token_error(GoogleServiceAuthError::AuthErrorNone()) {}
-SyncService::SyncTokenStatus::~SyncTokenStatus() {}
 
-}
+}  // namespace sync_driver