Examine source code of UserFocus

{
  "manifest_version": 2,
  "name": "Userfocus",
  "description": "Userfocus helps you to take live notes, annotate, react, share feedback and helps you to build user-centric products",
  "version": "0.0.3",
  "icons": {
    "64": "icons/icon_64.png",
    "128": "icons/icon.png"
  },
  "background": {
    "scripts": [
      "browser-polyfill.min.js",
      "background_script.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "64": "icons/icon_64.png",
      "128": "icons/icon.png"
    },
    "default_title": "Open live notes"
  }
}