Examine source code of SpotifyGenreDisplay

{
  "manifest_version": 2,
  "name": "SpotifyWebDisplayArtistGenre",
  "version": "1.1",
  "description": "This extension display the genre of the current artist on Spotify Web (only).",
  "icons": {
    "48": "logo.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://open.spotify.com/*"
      ],
      "js": [
        "script.js"
      ]
    }
  ],
  "browser_action": {
    "default_popup": "popup.html"
  },
  "permissions": [
    "storage",
    "https://accounts.spotify.com/*",
    "https://api.spotify.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{b7eff2f6-49fe-46f5-bbea-19dce276dcc8}"
    }
  }
}