ONC: Remove the top level fields NameServers and SearchDomains.

chromeos/network/onc/onc_validator.cc

Index: chromeos/network/onc/onc_validator.cc
diff --git a/chromeos/network/onc/onc_validator.cc b/chromeos/network/onc/onc_validator.cc
index fd55b296a793d34021525a67dcb61364a7f470dd..60a863c7f8064863270ed368771ab83518ed7255 100644
--- a/chromeos/network/onc/onc_validator.cc
+++ b/chromeos/network/onc/onc_validator.cc
@@ -608,8 +608,10 @@ bool Validator::ValidateIPConfig(base::DictionaryValue* result) {
   }
 
   bool all_required_exist = RequireField(*result, kIPAddress) &&
-                            RequireField(*result, kRoutingPrefix) &&
                             RequireField(*result, ::onc::ipconfig::kType);
+  if (result->HasKey(kIPAddress))
+    all_required_exist &= RequireField(*result, kRoutingPrefix);
+
 
   return !error_on_missing_field_ || all_required_exist;
 }