Re-add "ip_address" field to Mac MDNS response fields.

cl/1436373002 removed this field from the response, which created
inconsistent behavior between service_discovery_client_impl.cc
and service_discovery_client_mac.mm.

Also added test expectations to catch the regression.

BUG=560448
R=vitalybuka@chromium.org
CC=wez@chromium.org

Review URL: https://codereview.chromium.org/1467393002

Cr-Commit-Position: refs/heads/master@{#361187}

chrome/browser/local_discovery/service_discovery_client_mac.mm

@@ -352,6 +352,7 @@ void ServiceResolverImplMac::NetServiceContainer::OnResolveUpdate(
     if (end_point.FromSockAddr(socket, length)) {
       service_description_.address =
           net::HostPortPair::FromIPEndPoint(end_point);
+      service_description_.ip_address = end_point.address();
       break;
     }
   }

chrome/browser/local_discovery/service_discovery_client_mac_unittest.mm

@@ -147,8 +147,9 @@ TEST_F(ServiceDiscoveryClientMacTest, ServiceResolver) {
 
   EXPECT_EQ(1, num_resolves_);
   EXPECT_EQ(2u, last_service_description_.metadata.size());
-  EXPECT_EQ(kIp, last_service_description_.address.host());
+  EXPECT_EQ(ip_address, last_service_description_.ip_address);
   EXPECT_EQ(kPort, last_service_description_.address.port());
+  EXPECT_EQ(kIp, last_service_description_.address.host());
 }
 
 }  // namespace local_discovery