Examine source code of Ultimate Chords

{
  "manifest_version": 2,
  "name": "Ultimate Chords",
  "version": "1.2resigned1",
  "description": "Better chords for ultimate guitar",
  "content_scripts": [
    {
      "matches": [
        "*://*.ultimate-guitar.com/*"
      ],
      "js": [
        "index.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{03f8e590-d12b-4894-bb4c-8d4fde7fda2a}"
    }
  }
}