Fast-fail WPAD detection.

net/dns/host_resolver_impl.cc

 // Copyright (c) 2012 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/dns/host_resolver_impl.h"
 
 #if defined(OS_WIN)
 #include <Winsock2.h>
 #elif defined(OS_POSIX)
 #include <netdb.h>
@@ skipping 1343 matching lines @@
       DNS_HISTOGRAM_BY_PRIORITY("AsyncDNS.JobQueueTime", priority(),
                                 queue_time);
       DNS_HISTOGRAM_BY_PRIORITY("AsyncDNS.JobQueueTimeAfterChange", priority(),
                                 queue_time_after_change);
     } else {
       DNS_HISTOGRAM_BY_PRIORITY("DNS.JobQueueTime", priority(), queue_time);
       DNS_HISTOGRAM_BY_PRIORITY("DNS.JobQueueTimeAfterChange", priority(),
                                 queue_time_after_change);
     }
 
+    bool native_only = key_.host_resolver_flags & HOST_RESOLVER_SYSTEM_ONLY;

[szym, 2013/09/16 22:15:54]

|system_only|

[Elly Fong-Jones, 2013/09/17 19:20:23]

Done.

+
     // Caution: Job::Start must not complete synchronously.
-    if (had_dns_config_ && !ResemblesMulticastDNSName(key_.hostname)) {
+    if (!native_only && had_dns_config_ &&
+        !ResemblesMulticastDNSName(key_.hostname)) {
       StartDnsTask();
     } else {
       StartProcTask();
     }
   }
 
   // TODO(szym): Since DnsTransaction does not consume threads, we can increase
   // the limits on |dispatcher_|. But in order to keep the number of WorkerPool
   // threads low, we will need to use an "inner" PrioritizedDispatcher with
   // tighter limits.
@@ skipping 821 matching lines @@
   }
   DnsConfig dns_config;
   NetworkChangeNotifier::GetDnsConfig(&dns_config);
   dns_client_->SetConfig(dns_config);
   num_dns_failures_ = 0;
   if (dns_client_->GetConfig())
     UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true);
 }
 
 }  // namespace net