Add Cronet experimental option to disable ipv6

components/cronet/url_request_context_config_unittest.cc

 // Copyright 2015 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 "components/cronet/url_request_context_config.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/values.h"
 #include "net/cert/cert_verifier.h"
@@ skipping 33 matching lines @@
       "{\"QUIC\":{\"max_server_configs_stored_in_properties\":2,"
       "\"delay_tcp_race\":true,"
       "\"prefer_aes\":true,"
       "\"user_agent_id\":\"Custom QUIC UAID\","
       "\"idle_connection_timeout_seconds\":300,"
       "\"close_sessions_on_ip_change\":true,"
       "\"race_cert_verification\":true,"
       "\"connection_options\":\"TIME,TBBR,REJ\"},"
       "\"AsyncDNS\":{\"enable\":true},"
       "\"HostResolverRules\":{\"host_resolver_rules\":"
-      "\"MAP * 127.0.0.1\"}}",
+      "\"MAP * 127.0.0.1\"},"
+      // See http://crbug.com/696569.
+      "\"disable_ipv6\":true}",
       // Data reduction proxy key.
       "",
       // Data reduction proxy.
       "",
       // Fallback data reduction proxy.
       "",
       // Data reduction proxy secure proxy check URL.
       "",
       // MockCertVerifier to use for testing purposes.
       std::unique_ptr<net::CertVerifier>(),
@@ skipping 39 matching lines @@
 
   EXPECT_TRUE(params->quic_close_sessions_on_ip_change);
   EXPECT_FALSE(params->quic_migrate_sessions_on_network_change);
 
   // Check race_cert_verification.
   EXPECT_TRUE(params->quic_race_cert_verification);
 
   // Check AsyncDNS resolver is enabled.
   EXPECT_TRUE(context->host_resolver()->GetDnsConfigAsValue());
 
+  // Check IPv6 is disabled.
+  EXPECT_EQ(net::ADDRESS_FAMILY_IPV4,
+            context->host_resolver()->GetDefaultAddressFamily());
+
   net::HostResolver::RequestInfo info(net::HostPortPair("abcde", 80));
   net::AddressList addresses;
   EXPECT_EQ(net::OK, context->host_resolver()->ResolveFromCache(
                          info, &addresses, net::NetLogWithSource()));
 }
 
 TEST(URLRequestContextConfigTest, SetQuicConnectionMigrationOptions) {
   URLRequestContextConfig config(
       // Enable QUIC.
       true,
@@ skipping 47 matching lines @@
       context->GetNetworkSessionParams();
 
   EXPECT_FALSE(params->quic_close_sessions_on_ip_change);
   EXPECT_TRUE(params->quic_migrate_sessions_on_network_change);
   EXPECT_TRUE(params->quic_migrate_sessions_early);
 }
 
 // See stale_host_resolver_unittest.cc for test of StaleDNS options.
 
 }  // namespace cronet