anchor.diff:    }
   
     void _registerDesignerProxyListener() {
  -    chrome.runtime.onMessage.listen((event) {
  +    chrome.runtime.onMessage.listen((chrome.OnMessageEvent event) {
         // TODO(ussuri): Check the sender?
         if (event.message['type'] == 'export_code_response') {
           _codeExported.complete("${event.message['code']}");
  
positive.code:   @override
    void attached() {
      super.attached();
    }
  
    Future load() {
  
negative.code:   }
  
    void _onWebviewContentLoad(_) {
      _tweakDesignerUI();
      _injectDesignerProxy().then((_) => _webviewReady.complete());
    }
  
    void _tweakDesignerUI() {
      // TODO(ussuri): Some of this will become unnecessary once BUG #3467 is
      // resolved.
      _insertCssIntoWebview(r'''
          /* Reduce the initial font sizes */
          html /deep/ *, html /deep/ #tabs > * {
            font-size: 13px;
          }
  