Cleanup: Pass std::string as const reference if possible

net/dns/mdns_client_impl.cc

Index: net/dns/mdns_client_impl.cc
diff --git a/net/dns/mdns_client_impl.cc b/net/dns/mdns_client_impl.cc
index 9e464ed7c056ffa69d3bc490c48de65e42b6be56..053d4fe3861a4f57fcc38d7d57cb01e39538ae70 100644
--- a/net/dns/mdns_client_impl.cc
+++ b/net/dns/mdns_client_impl.cc
@@ -212,7 +212,7 @@ bool MDnsClientImpl::Core::Init(MDnsSocketFactory* socket_factory) {
   return connection_->Init(socket_factory);
 }
 
-bool MDnsClientImpl::Core::SendQuery(uint16 rrtype, std::string name) {
+bool MDnsClientImpl::Core::SendQuery(uint16 rrtype, const std::string& name) {
   std::string name_dns;
   if (!DNSDomainFromDot(name, &name_dns))
     return false;