chrome.runtime.onMessage.addListener(
    function(request, sender, sendResponse) {
      if (request.contentScriptQuery == "queryPrice") {
        var url = "https://pixelboii.wtf/steamvalue.json";
        var skinFullName = request.itemURL;
        fetch(url)
            .then(res => res.json())
            .then(price => {
              sendResponse(price.items_list[skinFullName].price["7_days"].average);
            })
            .catch(err => { throw err });
        return true;  // Will respond asynchronously.
      }
    });