HostResolver supports optional CNAME lookups.

chrome/browser/intranet_redirect_detector.h

Index: chrome/browser/intranet_redirect_detector.h
diff --git a/chrome/browser/intranet_redirect_detector.h b/chrome/browser/intranet_redirect_detector.h
index f1e38aef3bea1e2e82105cc07d33fc0a95f1f813..b8c5dcaac5d2ceddba05c02bf6265044493d1933 100644
--- a/chrome/browser/intranet_redirect_detector.h
+++ b/chrome/browser/intranet_redirect_detector.h
@@ -100,6 +100,7 @@ class IntranetRedirectHostResolverProc : public net::HostResolverProc {
 
   virtual int Resolve(const std::string& host,
                       net::AddressFamily address_family,
+                      net::HostResolverFlags host_resolver_flags,
                       net::AddressList* addrlist);
 };