Examine source code of Bandcamp+

{
  "name": "Bandcamp+",
  "short_name": "bandcamp-plus",
  "description": "Add multiple features to bandcamp.com",
  "version": "3.4.1",
  "manifest_version": 2,
  "icons": {
    "512": "assets/bandcamp-plus-icon.png"
  },
  "browser_action": {
    "default_title": "Bandcamp+",
    "default_icon": {
      "512": "assets/bandcamp-plus-icon.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.bandcamp.com/*"
      ],
      "js": [
        "scripts/content.js"
      ],
      "css": [
        "assets/content.css"
      ],
      "run_at": "document_start",
      "all_frames": false
    }
  ],
  "permissions": [
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{891ed2be-6ca9-47d1-9466-1595afa33b80}"
    }
  }
}