Detect domain-specific resolvers on OS X and disable DnsClient in such cases.

chrome/browser/net/dns_probe_service.cc

Index: chrome/browser/net/dns_probe_service.cc
diff --git a/chrome/browser/net/dns_probe_service.cc b/chrome/browser/net/dns_probe_service.cc
index c2fe4ae60103f4733e4bfe64f553fbaebe869bb4..d004ff26fd5aa1ff44bbbd43d4e2a29038bbb0d6 100644
--- a/chrome/browser/net/dns_probe_service.cc
+++ b/chrome/browser/net/dns_probe_service.cc
@@ -134,6 +134,7 @@ void DnsProbeService::SetSystemClientToCurrentConfig() {
   system_config.search.clear();
   system_config.attempts = 1;
   system_config.randomize_ports = false;
+  system_config.unhandled_options = false;

[mmenke, 2013/08/19 14:12:04]

Wonder if we should just skip the probe in this case...  Not a concern for this
CL.

[szym, 2013/08/19 14:26:16]

What does the prober do if there's no system config? If it fails gracefully,
I'll remove this line.

[mmenke, 2013/08/19 14:54:03]

DnsProbeRunner::RunProbe checks if the transaction factory is NULL, and if so,
passes along an "unknown" result.

[szym, 2013/08/20 18:55:34]

Removed.

 
   scoped_ptr<DnsClient> system_client(DnsClient::CreateClient(NULL));
   system_client->SetConfig(system_config);