Convert //sync from scoped_ptr to std::unique_ptr

sync/api/syncable_service.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/api/syncable_service.h"
 
 namespace syncer {
 
 SyncableService::~SyncableService() {}
 
-scoped_ptr<AttachmentStoreForSync>
+std::unique_ptr<AttachmentStoreForSync>
 SyncableService::GetAttachmentStoreForSync() {
-  return scoped_ptr<AttachmentStoreForSync>();
+  return std::unique_ptr<AttachmentStoreForSync>();
 }
 
 void SyncableService::SetAttachmentService(
-    scoped_ptr<AttachmentService> attachment_service) {
-}
+    std::unique_ptr<AttachmentService> attachment_service) {}
 
 }  // namespace syncer