Examine source code of Simple Clicker pooker

{
  "manifest_version": 2,
  "name": "Simple Clicker",
  "version": "1.0",
  "description": "A simple clicker game extension for Firefox",
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Simple Clicker",
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    }
  },
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b66f6a61-ad2c-4aaa-bcb4-e64052e08afb}"
    }
  }
}