Examine source code of DarkCloudV2

{
  "manifest_version": 2,
  "name": "DarkCloudV2 - SoundCloud Dark Mode",
  "version": "1.7.0",
  "description": "Changes soundcloud.com to a dark theme.",
  "icons": {
    "256": "icons/logo.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.soundcloud.com/*"
      ],
      "exclude_matches": [
        "*://*.soundcloud.com/settings/connections"
      ],
      "css": [
        "dark.css"
      ]
    }
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "256": "icons/logo.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "darkcloud@example.com"
    }
  }
}