[net/dns] Test IPv6 support via UDP connect

After this CL, the effective address family will be determined by
the UDP connect test rather than the last interface enumeration probe.

BUG=223876

Review URL: https://codereview.chromium.org/14161008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@195406 0039d316-1c4b-4281-b951-d872f2087c98

net/dns/host_resolver_impl.cc

@@ -2054,13 +2054,15 @@ HostResolverImpl::Key HostResolverImpl::GetEffectiveKeyForRequest(
   AddressFamily effective_address_family = info.address_family();
 
   if (info.address_family() == ADDRESS_FAMILY_UNSPECIFIED) {
+    if (ipv6_probe_monitoring_) {
       base::TimeTicks start_time = base::TimeTicks::Now();
       // Google DNS address.
       const uint8 kIPv6Address[] =
           { 0x20, 0x01, 0x48, 0x60, 0x48, 0x60, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x88, 0x88 };
-    bool rv6 = IsGloballyReachable(
-        IPAddressNumber(kIPv6Address, kIPv6Address + arraysize(kIPv6Address)));
+      IPAddressNumber address(kIPv6Address,
+                              kIPv6Address + arraysize(kIPv6Address));
+      bool rv6 = IsGloballyReachable(address);
 
       UMA_HISTOGRAM_TIMES("Net.IPv6ConnectDuration",
                           base::TimeTicks::Now() - start_time);
@@ -2070,15 +2072,14 @@ HostResolverImpl::Key HostResolverImpl::GetEffectiveKeyForRequest(
       } else {
         UMA_HISTOGRAM_BOOLEAN("Net.IPv6ConnectFailureMatch",
             default_address_family_ != ADDRESS_FAMILY_UNSPECIFIED);
-    }
-  }
 
-  if (effective_address_family == ADDRESS_FAMILY_UNSPECIFIED &&
-      default_address_family_ != ADDRESS_FAMILY_UNSPECIFIED) {
-    effective_address_family = default_address_family_;
-    if (ipv6_probe_monitoring_)
+        effective_address_family = ADDRESS_FAMILY_IPV4;
         effective_flags |= HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6;
       }
+    } else {
+      effective_address_family = default_address_family_;
+    }
+  }
 
   return Key(info.hostname(), effective_address_family, effective_flags);
 }