Update from https://crrev.com/316786

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 31 matching lines @@
 #include "net/base/net_util.h"
 #include "net/dns/address_sorter.h"
 #include "net/dns/dns_client.h"
 #include "net/dns/dns_config_service.h"
 #include "net/dns/dns_protocol.h"
 #include "net/dns/dns_response.h"
 #include "net/dns/dns_transaction.h"
 #include "net/dns/host_resolver_proc.h"
 #include "net/socket/client_socket_factory.h"
 #include "net/udp/datagram_client_socket.h"
+#include "url/url_canon_ip.h"
 
 #if defined(OS_WIN)
 #include "net/base/winsock_init.h"
 #endif
 
 namespace net {
 
 namespace {
 
 // Limit the size of hostnames that will be resolved to combat issues in
@@ skipping 2085 matching lines @@
   }
 }
 
 HostResolverImpl::Key HostResolverImpl::GetEffectiveKeyForRequest(
     const RequestInfo& info, const BoundNetLog& net_log) const {
   HostResolverFlags effective_flags =
       info.host_resolver_flags() | additional_resolver_flags_;
   AddressFamily effective_address_family = info.address_family();
 
   if (info.address_family() == ADDRESS_FAMILY_UNSPECIFIED) {
-    if (probe_ipv6_support_ && !use_local_ipv6_) {
+    unsigned char ip_number[4];
+    url::Component host_comp(0, info.hostname().size());
+    int num_components;
+    if (probe_ipv6_support_ && !use_local_ipv6_ &&
+        // Don't bother IPv6 probing when resolving IPv4 literals.
+        url::IPv4AddressToNumber(info.hostname().c_str(), host_comp, ip_number,
+                                 &num_components) != url::CanonHostInfo::IPV4) {
       // Google DNS address.
       const uint8 kIPv6Address[] =
           { 0x20, 0x01, 0x48, 0x60, 0x48, 0x60, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x88, 0x88 };
       IPAddressNumber address(kIPv6Address,
                               kIPv6Address + arraysize(kIPv6Address));
       BoundNetLog probe_net_log = BoundNetLog::Make(
           net_log.net_log(), NetLog::SOURCE_IPV6_REACHABILITY_CHECK);
       probe_net_log.BeginEvent(NetLog::TYPE_IPV6_REACHABILITY_CHECK,
                                net_log.source().ToEventParametersCallback());
@@ skipping 188 matching lines @@
     dns_client_->SetConfig(dns_config);
     num_dns_failures_ = 0;
     if (dns_client_->GetConfig())
       UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true);
   }
 
   AbortDnsTasks();
 }
 
 }  // namespace net