Examine source code of Gargamelify

{
  "manifest_version": 2,
  "name": "Gargamelify",
  "version": "0.4",
  "description": "Replace he who must not be named with Gargamel ",
  "icons": {
    "48": "icons/gargamelify-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "gargamelify.js"
      ]
    }
  ]
}