Qualify uses of std::string

PiperOrigin-RevId: 320101350
Change-Id: I9ab086e0d49ba7ec55af402d3df705c778522376
diff --git a/tensorflow/stream_executor/plugin_registry.cc b/tensorflow/stream_executor/plugin_registry.cc
index 4f85f92..058be75 100644
--- a/tensorflow/stream_executor/plugin_registry.cc
+++ b/tensorflow/stream_executor/plugin_registry.cc
@@ -188,7 +188,7 @@
                                                                               \
   template port::Status                                                       \
   PluginRegistry::RegisterFactoryInternal<PluginRegistry::FACTORY_TYPE>(      \
-      PluginId plugin_id, const string& plugin_name,                          \
+      PluginId plugin_id, const std::string& plugin_name,                     \
       PluginRegistry::FACTORY_TYPE factory,                                   \
       std::map<PluginId, PluginRegistry::FACTORY_TYPE>* factories);           \
                                                                               \