Convert //sync from scoped_ptr to std::unique_ptr

sync/api/syncable_service.cc

Index: sync/api/syncable_service.cc
diff --git a/sync/api/syncable_service.cc b/sync/api/syncable_service.cc
index a5d67c4d6591639daa3693564134a214027f9859..cbad406794b3c41fcc7ea9f4f7d0570fcaa3651a 100644
--- a/sync/api/syncable_service.cc
+++ b/sync/api/syncable_service.cc
@@ -8,13 +8,12 @@ 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