Fix incorrect check for expansion of {{bundle_root_dir}}

Bug: none
Change-Id: Ibae9c9a6ca2109f300e0f621c07e620cb42f27a5
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/8740
Commit-Queue: Brett Wilson <brettw@chromium.org>
Reviewed-by: Brett Wilson <brettw@chromium.org>
diff --git a/src/gn/bundle_file_rule.cc b/src/gn/bundle_file_rule.cc
index 4c4e96e..719e8aa 100644
--- a/src/gn/bundle_file_rule.cc
+++ b/src/gn/bundle_file_rule.cc
@@ -54,7 +54,7 @@
     if (subrange.type == &SubstitutionLiteral) {
       output_path.append(subrange.literal);
     } else if (subrange.type == &SubstitutionBundleRootDir) {
-      if (bundle_data.contents_dir().is_null()) {
+      if (bundle_data.root_dir().is_null()) {
         *err = ErrMissingPropertyForExpansion(settings, target, this,
                                               variables::kBundleRootDir);
         return false;