Use FileWatcher to watch system resolver config, on systems that require...

net/base/host_resolver_proc.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 "net/base/host_resolver_proc.h"
 
 #include "build/build_config.h"
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
 #include <resolv.h>
@@ skipping 178 matching lines @@
   // loopback addresses.
   if (host_resolver_flags & HOST_RESOLVER_LOOPBACK_ONLY)
     hints.ai_flags &= ~AI_ADDRCONFIG;
 
   if (host_resolver_flags & HOST_RESOLVER_CANONNAME)
     hints.ai_flags |= AI_CANONNAME;
 
   // Restrict result set to only this socket type to avoid duplicates.
   hints.ai_socktype = SOCK_STREAM;
 
+#if WATCH_RESOLV_CONF
+  if (ResolvConfUpdated())
+    res_ninit(&_res);
+#endif
+
+  bool should_retry = false;
   int err = getaddrinfo(host.c_str(), NULL, &hints, &ai);
-  bool should_retry = false;
-#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
+#if WATCH_RESOLV_CONF
   // If we fail, re-initialise the resolver just in case there have been any
   // changes to /etc/resolv.conf and retry. See http://crbug.com/11380 for info.
   if (err && DnsReloadTimerHasExpired()) {
     // When there's no network connection, _res may not be initialized by
     // getaddrinfo. Therefore, we call res_nclose only when there are ns
     // entries.
     if (_res.nscount > 0)
       res_nclose(&_res);
     if (!res_ninit(&_res))
       should_retry = true;
@@ skipping 42 matching lines @@
 #endif
 
     return ERR_NAME_NOT_RESOLVED;
   }
 
   addrlist->Adopt(ai);
   return OK;
 }
 
 }  // namespace net