ubsan: Don’t call v[0] on empty vectors

util/mach/child_port_handshake.cc

Index: util/mach/child_port_handshake.cc
diff --git a/util/mach/child_port_handshake.cc b/util/mach/child_port_handshake.cc
index eedcf47b267fb6e477017fe42bee221c82ce6b38..efe1ea8a7ae0be7762249cef3ca22e9a53402ce9 100644
--- a/util/mach/child_port_handshake.cc
+++ b/util/mach/child_port_handshake.cc
@@ -319,8 +319,8 @@ void ChildPortHandshake::RunClientInternal_ReadPipe(int pipe_read,
   DCHECK_LT(service_name_length,
             implicit_cast<uint32_t>(BOOTSTRAP_MAX_NAME_LEN));
 
-  if (service_name_length > 0) {
-    service_name->resize(service_name_length);
+  service_name->resize(service_name_length);
+  if (!service_name->empty()) {
     CheckedReadFile(pipe_read, &(*service_name)[0], service_name_length);
   }
 }