Examine source code of TimeLimit

{
  "manifest_version": 2,
  "name": "TimeLimit",
  "version": "1.0",
  "description": "Set limits on the time you spend on distracting websites to enhance productivity.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{cf91567a-5f6b-4b5f-b36c-ca7230b4148f}"
    }
  }
}