Examine source code of Adfilter

{
  "manifest_version": 2,
  "name": "Adfilter",
  "version": "1.3",
  "description": "Filters out the ad results from search results",
  "icons": {
    "96": "icons/a.jpg"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "onebond23@gmail.com"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.google.com/*",
        "https://duckduckgo.com/*"
      ],
      "js": [
        "adfilter.js"
      ]
    }
  ]
}