Examine source code of oknext

{
  "manifest_version": 2,
  "name": "oknext",
  "version": "1.0",
  "description": "Remotely go to next song on some streaming websites (currently YouTube and Spotify)",
  "short_name": "oknext",
  "icons": {
    "16": "icons/oknext-16.png",
    "48": "icons/oknext-48.png",
    "128": "icons/oknext-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/watch*",
        "http://localhost/*",
        "*://*.spotify.com/*"
      ],
      "js": [
        "oknext.js"
      ]
    }
  ],
  "permissions": [
    "storage"
  ],
  "options_ui": {
    "page": "options.html"
  }
}