Do not ship bundled zlib headers. Electron uses the system zlib, and anyone compiling against it should also.
--- a/third_party/electron_node/BUILD.gn
+++ b/third_party/electron_node/BUILD.gn
@@ -417,7 +417,6 @@
 
 group("copy_headers") {
   public_deps = header_groups + [
-                  ":zlib_headers",
                   ":node_gypi_headers",
                   ":node_version_header",
                 ]