Examine source code of Year Progress Tracker

{
  "manifest_version": 3,
  "name": "Year Progress Tracker",
  "author": "Dhamith Kumara",
  "version": "1.0",
  "description": "Shows how much of the year is completed with a real time countdown.",
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/16.png",
      "48": "images/48.png",
      "128": "images/128.png"
    }
  },
  "icons": {
    "16": "images/16.png",
    "48": "images/48.png",
    "128": "images/128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.mozilla.org/*"
      ],
      "js": [
        "background.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "bdhamithkumara@gmail.com",
      "strict_min_version": "58.0"
    }
  }
}