Examine source code of Spotify AdMute

{
  "manifest_version": 2,
  "name": "Spotify AdMute",
  "version": "7.2",
  "description": "Mutes Spotify web player during ads",
  "content_scripts": [
    {
      "matches": [
        "*://open.spotify.com/*"
      ],
      "js": [
        "admute.js"
      ]
    }
  ]
}