Examine source code of remove-premium-spotify

{
  "description": "Remove the try premium button from Spotify",
  "manifest_version": 2,
  "name": "remove-premium-spotify",
  "version": "1.0",
  "homepage_url": "https://github.com/AlgumCorrupto/remove-spotify",
  "content_scripts": [
    {
      "matches": [
        "*://*.spotify.com/*"
      ],
      "js": [
        "remove.js"
      ]
    }
  ],
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{af0db82a-41c5-4bcf-9ad6-98b30b4e199e}"
    }
  }
}