Examine source code of Task Timer v6

{
  "manifest_version": 2,
  "name": "Task Timer",
  "version": "1.0",
  "description": "Set a timer for your tasks and stay productive.",
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icon.png"
    }
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7f0c5b52-f1d7-460a-8af7-c978e10cd55d}"
    }
  }
}