Examine source code of spotifyMuted

{
  "manifest_version": 2,
  "name": "spotifyMuted",
  "version": "1.0.2",
  "description": "Mutes the browser when spotify puts advertisements.",
  "icons": {
    "48": "icons/icons.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://open.spotify.com/*"
      ],
      "js": [
        "spotify.js"
      ]
    }
  ]
}