Examine source code of vmo audio normalizer

{
  "name": "__MSG_name__",
  "description": "__MSG_description__",
  "version": "1.3resigned1",
  "manifest_version": 2,
  "default_locale": "en",
  "applications": {
    "gecko": {
      "id": "vmo-audio-normalizer@est31.github.io",
      "strict_min_version": "63.0"
    }
  },
  "icons": {
    "16": "icons/icon.svg",
    "48": "icons/icon.svg",
    "128": "icons/icon.svg"
  },
  "content_scripts": [
    {
      "matches": [
        "*://voice.mozilla.org/*"
      ],
      "run_at": "document_end",
      "js": [
        "normalizer.js"
      ]
    }
  ],
  "permissions": [
    "*://*.amazonaws.com/*"
  ]
}