old_contents: chrome.contextMenus.create(
      {
          "title": "Define '%s'",
          "contexts":["selection"],
          "onclick": function(info, tab){
              chrome.tabs.create(
                  {url: "http://www.google.com/search?q=define:" + info.selectionText
              });
          }
  });
  
new_contents: chrome.contextMenus.create(
      {
          "title": "Define \"%s\"",
          "contexts":["selection"],
          "onclick": function(info, tab){
              chrome.tabs.create(
                  {url: "http://www.google.com/search?q=define:" + info.selectionText
              });
          }
  });
  
subject: Use double quotes in the context menu, for consistency with Chrome's "Search Google for ..."