Examine source code of My Basic Extension

{
  "manifest_version": 2,
  "name": "My Basic Extension",
  "version": "1.0",
  "description": "A basic Firefox extension",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{407cdf8d-7ab8-48ff-9435-e216d3537531}"
    }
  }
}