Examine source code of Customized Image search

{
  "manifest_version": 2,
  "name": "Image Customized Search",
  "description": "Image according to format type.",
  "version": "1.1resigned1",
  "icons": {
    "48": "icons/download.png"
  },
  "permissions": [
    "contextMenus"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{242f2ece-dbe6-4f77-ad25-d09c0f28fde8}"
    }
  }
}