Cleanup: Pass std::string as const reference from chromeos/

chromeos/network/network_connection_handler.h

Index: chromeos/network/network_connection_handler.h
diff --git a/chromeos/network/network_connection_handler.h b/chromeos/network/network_connection_handler.h
index ddadf7a19e9df118f1cdb13cc07ba1b9847c1cbe..8b4e93f400d442c4865bb3382fd759b4ca751fe9 100644
--- a/chromeos/network/network_connection_handler.h
+++ b/chromeos/network/network_connection_handler.h
@@ -193,7 +193,11 @@ class CHROMEOS_EXPORT NetworkConnectionHandler
                                  const std::string& error_name,
                                  const std::string& error_message);
 
+  // Note: |service_path| is passed by value here, because in some cases
+  // the value may be located in the map and then it can be deleted, producing
+  // a reference to invalid memory.
   void CheckPendingRequest(const std::string service_path);
+
   void CheckAllPendingRequests();
 
   // Notify caller and observers that the connect request succeeded.