DNS: Don't use forbidden non-const reference

net/dns/dns_hosts.cc

Index: net/dns/dns_hosts.cc
diff --git a/net/dns/dns_hosts.cc b/net/dns/dns_hosts.cc
index b4d213b80c451fa24935473b53a720732f8ede7e..697ea148e007f111c368b4b53d12d09daab1d780 100644
--- a/net/dns/dns_hosts.cc
+++ b/net/dns/dns_hosts.cc
@@ -131,7 +131,6 @@ void ParseHostsWithCommaMode(const std::string& contents,
                              DnsHosts* dns_hosts,
                              ParseHostsCommaMode comma_mode) {
   CHECK(dns_hosts);
-  DnsHosts& hosts = *dns_hosts;
 
   StringPiece ip_text;
   IPAddressNumber ip;
@@ -156,9 +155,9 @@ void ParseHostsWithCommaMode(const std::string& contents,
     } else {
       DnsHostsKey key(parser.token().as_string(), family);
       base::StringToLowerASCII(&key.first);
-      IPAddressNumber& mapped_ip = hosts[key];
-      if (mapped_ip.empty())
-        mapped_ip = ip;
+      IPAddressNumber* mapped_ip = &(*dns_hosts)[key];
+      if (mapped_ip->empty())
+        *mapped_ip = ip;
       // else ignore this entry (first hit counts)
     }
   }