HostResolver supports optional CNAME lookups.

chrome/browser/intranet_redirect_detector.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/intranet_redirect_detector.h"
 
 #include "base/rand_util.h"
 #include "base/stl_util-inl.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 140 matching lines @@
   StartFetchesIfPossible();
 }
 
 IntranetRedirectHostResolverProc::IntranetRedirectHostResolverProc(
     net::HostResolverProc* previous)
     : net::HostResolverProc(previous) {
 }
 
 int IntranetRedirectHostResolverProc::Resolve(const std::string& host,
                                               net::AddressFamily address_family,
+                                              net::HostResolverFlags flags,
                                               net::AddressList* addrlist) {
   // We'd love to just ask the IntranetRedirectDetector, but we may not be on
   // the same thread.  So just use the heuristic that any all-lowercase a-z
   // hostname with the right number of characters is likely from the detector
   // (and thus should be blocked).
   return ((host.length() == IntranetRedirectDetector::kNumCharsInHostnames) &&
       (host.find_first_not_of("abcdefghijklmnopqrstuvwxyz") ==
           std::string::npos)) ?
       net::ERR_NAME_NOT_RESOLVED :
-      ResolveUsingPrevious(host, address_family, addrlist);
+      ResolveUsingPrevious(host, address_family, flags, addrlist);
 }