Examine source code of PassGen

{
  "manifest_version": 2,
  "name": "PassGen",
  "version": "2.0",
  "description": "Extensions who generate strong passwords for accounts. OpenSource",
  "homepage_url": "https://github.com/Nothelsel",
  "icons": {
    "96": "./icons/lock-96.png"
  },
  "permissions": [
    "clipboardRead",
    "clipboardWrite",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "54.0a1",
      "id": "{3cc346f4-12c4-4411-8a90-a9f9743a9c54}"
    }
  },
  "content_scripts": [
    {
      "exclude_matches": [
        "*://developer.mozilla.org/*"
      ],
      "matches": [
        "*://*.mozilla.org/*"
      ],
      "js": [
        "./popup/pop_passgen.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": "./icons/lock-96.png",
    "default_title": "PassGen",
    "default_popup": "./popup/pop_passgen.html"
  }
}