Examine source code of Internet Speed Test

{
  "manifest_version": 2,
  "name": "Internet Speed Test",
  "version": "1.0",
  "description": "Internet speed test, extension created with HTML, CSS and JavaScript. The extension will display the user's connection speed in terms of bits per second (bps), kilobits per second (kbps) and megabits per second (Mbps).",
  "browser_action": {
    "default_popup": "index.html"
  },
  "icons": {
    "48": "img/fast.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.mozilla.org/*"
      ],
      "js": [
        "script.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ed9b12f2-893e-4528-9abf-cc24b413a772}"
    }
  }
}