WebUI: Swap Uglify with Closure Compiler NodeJS version.

chrome/browser/resources/vulcanize_gn.py

Index: chrome/browser/resources/vulcanize_gn.py
diff --git a/chrome/browser/resources/vulcanize_gn.py b/chrome/browser/resources/vulcanize_gn.py
index 309ab32be4bb53533003a2116b68bdb96f1cee12..505ebc7531d982f08bec2538aa934512684e5242 100755
--- a/chrome/browser/resources/vulcanize_gn.py
+++ b/chrome/browser/resources/vulcanize_gn.py
@@ -172,9 +172,20 @@ def _vulcanize(in_folder, args):
     if not os.path.isfile(js_out_path):
       open(js_out_path, 'w').close()
 
-    node.RunNode([node_modules.PathToUglifyJs(), js_out_path,
-                  '--comments', '"/Copyright|license|LICENSE|\<\/?if/"',
-                  '--output', js_out_path])
+    # Rewrite licenses such that Closure Compiler will preserve them.
+    import rewrite_licenses
+    with open(js_out_path, 'r') as f:
+      output_data = rewrite_licenses.rewrite(f.read())
+
+    # Open file again with 'w' such that the previous contents are overwritten.
+    with open(js_out_path, 'w') as f:
+      f.write(output_data)
+      f.close()
+
+    output = node.RunNode([node_modules.PathToClosureCompiler(), js_out_path])
+    with open(js_out_path, 'w') as output_file:
+      output_file.write(output)
+
   finally:
     os.remove(tmp.name)