Examine source code of Swipe Back

{
  "manifest_version": 2,
  "name": "Swipe Back",
  "version": "2.0.0",
  "description": "Jump back/forward in the browser's history by swiping horizontally with two fingers on your touchpad. Mimics the default behaviour of Safari / Gnome Web.",
  "homepage_url": "https://github.com/anuejn/two-finger-history-jump",
  "icons": {
    "48": "icon.svg"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "index.js"
      ]
    }
  ]
}