[MD History] Vulcanize as part of GN build.

chrome/browser/resources/md_downloads/BUILD.gn

Index: chrome/browser/resources/md_downloads/BUILD.gn
diff --git a/chrome/browser/resources/md_downloads/BUILD.gn b/chrome/browser/resources/md_downloads/BUILD.gn
index 1dc2cabc98c67837cdcb83b77a6e8917715e9bb1..b0e28c97ae157bfaaa4ab6e69f4fee98354b3b6c 100644
--- a/chrome/browser/resources/md_downloads/BUILD.gn
+++ b/chrome/browser/resources/md_downloads/BUILD.gn
@@ -3,10 +3,18 @@ import("../vulcanize.gni")
 vulcanize("vulcanize") {
   host = "downloads"
   html_in_file = "downloads.html"
-  html_out_file = "vulcanized.html"
+  html_out_file = "vulcanized.html.unbuilt"
 
   input_type = "FOLDER"
   input = rebase_path(".", root_build_dir)
   js_out_file = "crisper.js"
   deps = []
 }
+
+css_build("build") {
+  input_files = [ "vulcanized.html.unbuilt" ]
+  output_files = [ "vulcanized.html" ]
+  deps = [
+    ":vulcanize",
+  ]
+}