Examine source code of codeTabber

{
  "manifest_version": 2,
  "name": "codeTabber",
  "description": "Switch between code panes on CodePen, JSFiddle, and other online code editors, right from the keyboard.",
  "version": "1.2resigned1",
  "short_name": "codeTabber",
  "icons": {
    "48": "codetabber48.png",
    "96": "codetabber96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.codepen.io/*",
        "*://*.cssdeck.com/*",
        "*://*.cssdesk.com/*",
        "*://*.dabblet.com/*",
        "*://*.jsbin.com/*",
        "*://*.jsfiddle.net/*",
        "*://*.kodtest.com/*",
        "*://*.liveweave.com/*",
        "*://*.rendera.herokuapp.com/*",
        "*://*.stackoverflow.com/*"
      ],
      "js": [
        "codetabber.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{b603117a-e5f3-4567-a0a9-63ebfc1b874a}"
    }
  }
}