Examine source code of Speedtest by Jalti.in

{
  "manifest_version": 2,
  "name": "Speedtest by Jalti.in",
  "description": "Test your Internet Bandwidth",
  "version": "3.0",
  "icons": {
    "16": "images/jalti_favicon-16.png",
    "32": "images/jalti_favicon-32.png",
    "48": "images/jalti_favicon-48.png",
    "128": "images/jalti_favicon-128.png"
  },
  "browser_action": {
    "default_icon": {
      "19": "images/jalti_favicon-19.png",
      "32": "images/jalti_favicon-32.png"
    },
    "default_title": "Jalti.in Speedtest",
    "default_popup": "index.html"
  }
}