Examine source code of Search on Google

{
  "manifest_version": 2,
  "name": "Search on Google",
  "version": "0.1",
  "description": "Add a search on Google button to duckduckgo search results",
  "content_scripts": [
    {
      "matches": [
        "*://duckduckgo.com/*"
      ],
      "js": [
        "index.js"
      ]
    }
  ]
}