Examine source code of ClearMind

{
  "manifest_version": 2,
  "name": "ClearMind",
  "version": "0.4",
  "description": "Removes ads and recommended videos from YouTube",
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "clearMind.js"
      ]
    }
  ]
}