Examine source code of YouTube Redirect to Embed

{
  "manifest_version": 2,
  "name": "YouTube Redirector",
  "version": "1.1.3",
  "description": "Redirect YouTube links from watch to embed format.",
  "icons": {
    "512": "icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Redirect YouTube Links"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{67c22efd-8396-46aa-94b3-86a06cb85396}"
    }
  }
}