Examine source code of YT Better Progress Bar

{
  "manifest_version": 2,
  "name": "YT Better Progress Bar",
  "version": "1.3",
  "description": "Replaces the awful pink progress bar with the old and better red one",
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "index.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{609efe56-4567-4187-b0d7-b166fcf02e88}"
    }
  }
}