Remove usage of FOR_EACH_OBSERVER macro in gin

gin/modules/module_registry.cc

Index: gin/modules/module_registry.cc
diff --git a/gin/modules/module_registry.cc b/gin/modules/module_registry.cc
index bf11ec8d7e5564423fe01911ed33d65d73498324..3e8b47597601d035919bbc419cef4a2628979df4 100644
--- a/gin/modules/module_registry.cc
+++ b/gin/modules/module_registry.cc
@@ -163,8 +163,8 @@ void ModuleRegistry::AddPendingModule(Isolate* isolate,
   const std::string pending_id = pending->id;
   const std::vector<std::string> pending_dependencies = pending->dependencies;
   AttemptToLoad(isolate, std::move(pending));
-  FOR_EACH_OBSERVER(ModuleRegistryObserver, observer_list_,
-                    OnDidAddPendingModule(pending_id, pending_dependencies));
+  for (auto& observer : observer_list_)
+    observer.OnDidAddPendingModule(pending_id, pending_dependencies);
 }
 
 void ModuleRegistry::LoadModule(Isolate* isolate,