Examine source code of Nyanize Extension

{
  "manifest_version": 2,
  "name": "Nyanize Extension",
  "short_name": "Nyanize",
  "version": "2.1",
  "description": "nyanize all website",
  "browser_action": {
    "default_title": "Nyanize Options",
    "default_icon": {
      "19": "img/gear19.png",
      "38": "img/gear38.png"
    },
    "default_popup": "html/main.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "js/content_script.js"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "storage"
  ]
}