Examine source code of RNPSign

{
  "manifest_version": 2,
  "name": "RNPSign",
  "description": "Essa extensão permite configurar certificados para fins de assinatura digital",
  "version": "1.1.4",
  "icons": {
    "16": "logo512.png",
    "48": "logo512.png",
    "128": "logo512.png"
  },
  "browser_action": {
    "default_icon": "logo512.png",
    "default_title": "Opções da RNPSign",
    "default_popup": "index.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "rnpsign@rnp.br",
      "strict_min_version": "50.0"
    }
  },
  "permissions": [
    "nativeMessaging",
    "http://*/",
    "https://*/"
  ]
}