core/form_filler/background.js

chrome.runtime.onMessage.addListener((request, sender, sendResponse) => {
    if (request.action === "fillForm") {
      chrome.tabs.query({active: true, currentWindow: true}, (tabs) => {
        chrome.tabs.sendMessage(tabs[0].id, {
          action: "fillFields",
          resumeData: request.data
        });
      });
    }
  });