[net/dns] Log canonical name when logging AddressList

R=mmenke@chromium.org

Bug: 884310
Change-Id: I0f14c7dfcb2a6c54e52ac4f18328095e4af78db2
Reviewed-on: https://chromium-review.googlesource.com/c/1300778Reviewed-by: Matt Menke <mmenke@chromium.org>
Commit-Queue: Asanka Herath <asanka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603063}

net/base/address_list.cc

@@ -28,6 +28,7 @@ std::unique_ptr<base::Value> NetLogAddressListCallback(
   }
 
   dict->Set("address_list", std::move(list));
+  dict->SetString("canonical_name", address_list->canonical_name());
   return std::move(dict);
 }