Examine source code of Image Rotation Preview

{
  "manifest_version": 2,
  "name": "Image Rotation Preview",
  "version": "1.0",
  "description": "Xoay ảnh trên trang web theo các góc 0°, 90°, 180°, 270° để xem thử.",
  "permissions": [
    "contextMenus"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "rotate.js"
      ],
      "css": [
        "rotate.css"
      ]
    }
  ],
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{cfdab702-504d-4ddf-b7bf-265ebc917142}"
    }
  }
}