Examine source code of Sign XML extension

{
  "name": "Sign XML extension",
  "version": "0.0.2",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "manifest_version": 2,
  "description": "Extension for signing XML files.",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "signxml@sris.sec.gov.mk",
      "strict_min_version": "55.0"
    }
  },
  "permissions": [
    "nativeMessaging"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://sris.sec.gov.mk/*",
        "https://sris-test.sec.gov.mk/*"
      ],
      "js": [
        "contentScript.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_action": {
    "default_title": "Sign XML extension"
  }
}