CPP bindings: DCHECK when a Callback is destructed without being invoked

services/view_manager/view_manager_service_apptest.cc

Index: services/view_manager/view_manager_service_apptest.cc
diff --git a/services/view_manager/view_manager_service_apptest.cc b/services/view_manager/view_manager_service_apptest.cc
index 01bdd0f0c03886b5e4dbffe682c288fc62ff6368..a3bcc26d7b571b3f1c89af0f254589c3e88723cd 100644
--- a/services/view_manager/view_manager_service_apptest.cc
+++ b/services/view_manager/view_manager_service_apptest.cc
@@ -333,6 +333,7 @@ class ViewManagerClientImpl : public mojo::ViewManagerClient,
                         EventPtr event,
                         const Callback<void()>& callback) override {
     tracker()->OnViewInputEvent(view_id, event.Pass());
+    callback.Run();
   }
   void OnViewSharedPropertyChanged(uint32_t view,
                                    const String& name,