Examine source code of Luffy4 One Piece theme

{
  "manifest_version": 2,
  "name": "Luffy4 One Piece theme",
  "version": "1.0",
  "description": "Over the course of his adventures, Luffy has gathered a diverse crew, each with their own dreams and goals. Together, they sail the Grand Line in search of adventure.",
  "icons": {
    "48": "icon.png"
  },
  "web_accessible_resources": [
    "background.jpg"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "permissions": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "{2300ac3f-fc68-4054-b585-31bfae4a207c}"
    }
  }
}