Examine source code of Focus Blocks

{
  "manifest_version": 2,
  "name": "Focus Blocks",
  "version": "1.2.1",
  "description": "25-5 minute Pomodoro cycles with audio bell and counter",
  "browser_specific_settings": {
    "gecko": {
      "id": "{0ed67dab-4673-4b1d-a268-40c0fc8c7f49}",
      "strict_min_version": "96.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "16": "img/icon-16.png",
    "32": "img/icon-32.png",
    "48": "img/icon-48.png",
    "96": "img/icon-96.png",
    "128": "img/icon-128.png"
  },
  "browser_action": {
    "default_popup": "ui/widget.html",
    "default_icon": {
      "16": "img/icon-16.png",
      "32": "img/icon-32.png",
      "48": "img/icon-48.png",
      "96": "img/icon-96.png",
      "128": "img/icon-128.png"
    }
  },
  "background": {
    "scripts": [
      "service/tracker.js"
    ]
  },
  "permissions": []
}