WebUI: Vulcanize MD Downloads at compile time using GN.

chrome/browser/BUILD.gn

Index: chrome/browser/BUILD.gn
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index 43cf6e0be8e2e76bb0c9e3e946daad17c98f9b2b..0b2316802c4e7322f83c7f17862be146eb637ec0 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -4146,6 +4146,10 @@ grit("resources") {
     "//url/mojo:url_mojom_origin__generator",
   ]
 
+  if (use_vulcanize) {
+    deps += [ "//chrome/browser/resources/md_downloads:vulcanize" ]
+  }
+
   if (safe_browsing_mode > 0) {
     deps +=
         [ "//chrome/browser/resources/safe_browsing:make_file_types_protobuf" ]