Examine source code of Focus Timer Popup

{
  "manifest_version": 2,
  "name": "Focus Timer Popup",
  "version": "1.0",
  "description": "A simple Pomodoro-style focus timer in a popup.",
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png",
    "default_title": "Focus Timer"
  },
  "permissions": [],
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4e70d8ba-e4ca-43ac-b7b6-b23e2f3d8392}"
    }
  }
}