Examine source code of yt-stretch

{
  "description": "Stretch shorts into longs",
  "manifest_version": 2,
  "name": "yt-stretch",
  "version": "1.0",
  "homepage_url": "https://github.com/dbowring/yt-stretch",
  "icons": {
    "48": "icon-48.svg"
  },
  "permissions": [
    "webNavigation",
    "webRequest",
    "webRequestBlocking",
    "https://www.youtube.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "57.0a1",
      "id": "{b5383268-d51a-44e3-bae2-884f40cb8249}"
    }
  }
}