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

net/base/ip_pattern_unittest.cc

Index: net/base/ip_pattern_unittest.cc
diff --git a/net/base/ip_pattern_unittest.cc b/net/base/ip_pattern_unittest.cc
index 5e06cd69a1c709928c2a2e73899bf3915723df88..feec18dd505806775049fffd589c3542c8b56a31 100644
--- a/net/base/ip_pattern_unittest.cc
+++ b/net/base/ip_pattern_unittest.cc
@@ -16,7 +16,7 @@ bool IsValidPattern(const std::string& pattern_text) {
   return pattern.ParsePattern(pattern_text);
 }
 
-bool CheckForMatch(const IPPattern& pattern, std::string address_text) {
+bool CheckForMatch(const IPPattern& pattern, const std::string& address_text) {
   IPAddressNumber address;
   EXPECT_TRUE(ParseIPLiteralToNumber(address_text, &address));
   return pattern.Match(address);