postinstall: fixed postinst_action_progress is NaN
am: 128936fb26

Change-Id: I1e9920c6ae1c30f58c5d693b7cc3cd66420481c4
diff --git a/payload_consumer/postinstall_runner_action.cc b/payload_consumer/postinstall_runner_action.cc
index cedecda..b6af131 100644
--- a/payload_consumer/postinstall_runner_action.cc
+++ b/payload_consumer/postinstall_runner_action.cc
@@ -264,7 +264,7 @@
 void PostinstallRunnerAction::ReportProgress(double frac) {
   if (!delegate_)
     return;
-  if (current_partition_ >= partition_weight_.size()) {
+  if (current_partition_ >= partition_weight_.size() || total_weight_ == 0) {
     delegate_->ProgressUpdate(1.);
     return;
   }