Resolve RFC 6761 localhost names to loopback

net/dns/host_resolver_impl.h

Index: net/dns/host_resolver_impl.h
diff --git a/net/dns/host_resolver_impl.h b/net/dns/host_resolver_impl.h
index e3b8ed7685ea5b935287a4a405e9769b45938ddf..b35281f079461b98d0cd169c0b0371baa9518b05 100644
--- a/net/dns/host_resolver_impl.h
+++ b/net/dns/host_resolver_impl.h
@@ -161,7 +161,8 @@ class NET_EXPORT HostResolverImpl
   // Helper used by |Resolve()| and |ResolveFromCache()|.  Performs IP
   // literal, cache and HOSTS lookup (if enabled), returns OK if successful,
   // ERR_NAME_NOT_RESOLVED if either hostname is invalid or IP literal is
-  // incompatible, ERR_DNS_CACHE_MISS if entry was not found in cache and HOSTS.
+  // incompatible, ERR_DNS_CACHE_MISS if entry was not found in cache and
+  // HOSTS and is not localhost.
   int ResolveHelper(const Key& key,
                     const RequestInfo& info,
                     const IPAddressNumber* ip_address,
@@ -190,6 +191,12 @@ class NET_EXPORT HostResolverImpl
                       const RequestInfo& info,
                       AddressList* addresses);
 
+  // If |key| is for a localhost name (RFC 6761), returns true and fills
+  // |addresses| with the loopback IP. Otherwise returns false.
+  bool ServeLocalhost(const Key& key,
+                      const RequestInfo& info,
+                      AddressList* addresses);
+
   // Callback from HaveOnlyLoopbackAddresses probe.
   void SetHaveOnlyLoopbackAddresses(bool result);