Examine source code of Piedwork

{
  "manifest_version": 2,
  "version": "1.1.3",
  "short_name": "Piedwork",
  "name": "Piedwork",
  "description": "Piedwork extension facilitates manager experience with Upwork and allows to cache job post cover letters for further usage.",
  "icons": {
    "16": "logo.png",
    "48": "logo.png",
    "128": "logo.png"
  },
  "permissions": [
    "storage",
    "https://www.upwork.com/",
    "*://*.piedwork.com/*",
    "http://localhost/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.upwork.com/*"
      ],
      "js": [
        "upwork.js"
      ]
    }
  ],
  "browser_action": {
    "default_popup": "index.html",
    "default_title": "Open the popup"
  }
}