Examine source code of Productivity Timer v3

{
  "manifest_version": 2,
  "name": "Productivity Timer",
  "version": "1.0",
  "description": "A customizable timer to boost productivity using the Pomodoro technique.",
  "icons": {
    "48": "icons/productivity-timer-icon-48.png"
  },
  "permissions": [],
  "browser_action": {
    "default_icon": "icons/productivity-timer-icon-48.png",
    "default_popup": "popup.html",
    "default_title": "Productivity Timer"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f2aea399-7588-461a-8dde-f843c2df61b5}"
    }
  }
}