Examine source code of Pomodoro clock extension

{
  "manifest_version": 3,
  "name": "Pomodoro clock",
  "version": "2.9.0",
  "description": "A simple pomodoro clock in your browser to hack your productivity.",
  "homepage_url": "https://github.com/macmorning/pomodoro-webext",
  "icons": {
    "48": "icons/clock-48.png",
    "128": "icons/clock-128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options.html"
  },
  "action": {
    "default_title": "Pomodoro",
    "default_icon": {
      "48": "icons/clock-48.png"
    },
    "default_popup": "pomodoro.html"
  },
  "permissions": [
    "storage",
    "notifications",
    "alarms"
  ],
  "optional_permissions": [
    "downloads",
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{710ec9db-6f38-4798-90b9-7486b2285bfb}"
    }
  }
}