Examine source code of AutoClose

{
  "manifest_version": 2,
  "name": "AutoClose",
  "version": "1.0.0",
  "description": "Automatically closes all tabs with a specified domain",
  "permissions": [
    "tabs",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "48": "assets/icon-48.png",
    "96": "assets/icon-96.png"
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{fd8d8d85-741c-455f-9c08-11b66be9b3a6}"
    }
  }
}