Examine source code of Assinador Web

{
  "manifest_version": 2,
  "name": "Assinador Web",
  "short_name": "assinador-web",
  "description": "Assinador digital",
  "version": "1.0.32",
  "author": "SEFAZ-AM",
  "browser_specific_settings": {
    "gecko": {
      "id": "assinador-web@sefaz.am.gov.br"
    }
  },
  "icons": {
    "16": "skin/icon-16.png",
    "48": "skin/icon-48.png",
    "128": "skin/icon-128.png"
  },
  "background": {
    "persistent": true,
    "scripts": [
      "content/page-action.js"
    ]
  },
  "browser_action": {
    "default_icon": "skin/icon-128.png",
    "default_title": "!",
    "default_popup": "html/popup.html"
  },
  "content_scripts": [
    {
      "js": [
        "content/assinador.js"
      ],
      "all_frames": true,
      "matches": [
        "http://*.am.gov.br/*",
        "https://*.am.gov.br/*",
        "http://*.intra.sefaz.am/*",
        "https://*.intra.sefaz.am/*",
        "http://localhost/*",
        "https://localhost/*"
      ]
    }
  ],
  "permissions": [
    "nativeMessaging",
    "http://*.am.gov.br/*",
    "https://*.am.gov.br/*",
    "http://*.intra.sefaz.am/*",
    "https://*.intra.sefaz.am/*",
    "http://localhost/*",
    "https://localhost/*"
  ],
  "web_accessible_resources": [
    "skin/icon-16.png",
    "skin/icon-48.png",
    "skin/icon-128.png",
    "content/onload.js"
  ]
}