Examine source code of MangaNav

{
  "manifest_version": 3,
  "name": "MangaNav",
  "version": "1.0.2",
  "description": "MangaNav is a Browser Extension that adds Previous/Next Page Navigation mapped to Left/Right Arrow Keys for Manga Sites that do not provide this Feature natively.",
  "icons": {
    "16": "src/icons/MangaNavIcon-16.png",
    "32": "src/icons/MangaNavIcon-32.png",
    "48": "src/icons/MangaNavIcon-48.png",
    "64": "src/icons/MangaNavIcon-64.png",
    "128": "src/icons/MangaNavIcon-128.png"
  },
  "action": {
    "default_title": "MangaNav",
    "default_icon": "src/icons/MangaNavAdd-256.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "src/manganav.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "src/background.js"
    ]
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "MangaNav@m-grohs",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}