Examine source code of YouTube Speed Toggle

{
  "manifest_version": 2,
  "name": "YouTube Speed Toggle",
  "version": "0.0.3",
  "author": "Gchatzz",
  "description": "Adds a button to toggle video playback speed on YouTube.",
  "permissions": [
    "activeTab",
    "webNavigation",
    "*://www.youtube.com/*"
  ],
  "icons": {
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{731386df-5eac-4cf5-9870-3d277506ba7b}"
    }
  }
}