Examine source code of Youtube 2x toggle

{
  "manifest_version": 2,
  "name": "Youtube 2x toggle",
  "version": "1.0.4",
  "description": "Add 1x/2x playback speed toggle to the Youtube video player bottom right panel.",
  "homepage_url": "https://github.com/pegov/youtube-2x-toggle",
  "icons": {
    "48": "icons/48.png",
    "96": "icons/96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "main.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "images/*.svg"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{56e4c783-3d4f-452f-9f76-c45a02153d69}"
    }
  }
}