Examine source code of ES

{
  "manifest_version": 2,
  "name": "ES",
  "version": "1.1.3",
  "description": "Adds lacking functionality",
  "icons": {
    "64": "icons/es.png"
  },
  "web_accessible_resources": [
    "images/google.png",
    "images/ddgo.svg"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://duckduckgo.com/?*"
      ],
      "js": [
        "js/ddgo_to_google.js"
      ],
      "css": [
        "css/ddgo.css"
      ]
    },
    {
      "matches": [
        "*://www.google.com/search*"
      ],
      "js": [
        "js/google_to_ddgo.js"
      ],
      "css": [
        "css/google.css"
      ]
    }
  ]
}