Examine source code of Disable WebRTC

{
  "name": "Disable WebRTC",
  "description": "This extension disables WebRTC in Firefox 57+",
  "version": "0.4resigned1",
  "manifest_version": 2,
  "permissions": [
    "privacy"
  ],
  "icons": {
    "32": "icon32.png",
    "48": "icon48.png",
    "64": "icon64.png",
    "128": "icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{64f73088-5156-43ae-94db-5a4701089ba3}"
    }
  }
}