[Sync] Allow sync start without sign-in if the local sync backend is on.

components/sync/driver/fake_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/fake_sync_service.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/values.h"
 #include "components/sync/driver/data_type_controller.h"
 #include "components/sync/syncable/base_transaction.h"
@@ skipping 12 matching lines @@
 }
 
 bool FakeSyncService::IsSyncAllowed() const {
   return false;
 }
 
 bool FakeSyncService::IsSyncActive() const {
   return false;
 }
 
+bool FakeSyncService::IsLocalSyncEnabled() const {
+  return false;
+}
+
 void FakeSyncService::TriggerRefresh(const ModelTypeSet& types) {}
 
 ModelTypeSet FakeSyncService::GetActiveDataTypes() const {
   return ModelTypeSet();
 }
 
 SyncClient* FakeSyncService::GetSyncClient() const {
   return nullptr;
 }
 
@@ skipping 161 matching lines @@
     TypeDebugInfoObserver* observer) {}
 
 base::WeakPtr<JsController> FakeSyncService::GetJsController() {
   return base::WeakPtr<JsController>();
 }
 
 void FakeSyncService::GetAllNodes(
     const base::Callback<void(std::unique_ptr<base::ListValue>)>& callback) {}
 
 }  // namespace syncer