AU: detect failure when using public key verification

download_action.cc

Index: download_action.cc
diff --git a/download_action.cc b/download_action.cc
index d6ae97dfefc5eec167fab74d725b7aba6ae85d33..9577047de5f49c55fc6d6540baf02edc50ba7a05 100644
--- a/download_action.cc
+++ b/download_action.cc
@@ -163,7 +163,8 @@ void DownloadAction::TransferComplete(HttpFetcher *fetcher, bool successful) {
     if (!install_plan_.is_full_update) {
       if (!delta_performer_->VerifyPayload("",
                                            install_plan_.download_hash,
-                                           install_plan_.size)) {
+                                           install_plan_.size,
+                                           NULL)) {
         LOG(ERROR) << "Download of " << install_plan_.download_url
                    << " failed due to payload verification error.";
         code = kActionCodeDownloadPayloadVerificationError;