HostResolverImpl will return ERR_NAME_NOT_RESOLVED instead of Ok if address list is empty

net/dns/host_resolver_impl.cc

Index: net/dns/host_resolver_impl.cc
diff --git a/net/dns/host_resolver_impl.cc b/net/dns/host_resolver_impl.cc
index 0aed70d6b75deb230261d520cd742f2f9bcb3ea1..95e03ba7a912a857586e0ceaf1c6845a4679820d 100644
--- a/net/dns/host_resolver_impl.cc
+++ b/net/dns/host_resolver_impl.cc
@@ -682,7 +682,11 @@ class HostResolverImpl::ProcTask
                         int error,
                         const int os_error) {
     DCHECK(origin_loop_->BelongsToCurrentThread());
-    DCHECK(error || !results.empty());
+    // If results are empty, we should return an error.
+    bool empty_list_on_ok = (error == OK && results.empty());
+    UMA_HISTOGRAM_BOOLEAN("DNS.EmptyAddressListAndNoError", empty_list_on_ok);
+    if (empty_list_on_ok)
+      error = ERR_NAME_NOT_RESOLVED;
 
     bool was_retry_attempt = attempt_number > 1;