Examine source code of Productivity Timer

{
  "manifest_version": 2,
  "name": "Productivity Timer",
  "version": "1.0",
  "description": "A simple Pomodoro timer to boost your productivity.",
  "icons": {
    "48": "icons/timer-icon-48.png"
  },
  "permissions": [
    "alarms"
  ],
  "browser_action": {
    "default_icon": "icons/timer-icon-48.png",
    "default_popup": "popup.html",
    "default_title": "Productivity Timer"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1f88ad16-bb9e-4497-ac44-d6a6baec8cf3}"
    }
  }
}