Examine source code of YT Speed Controller

{
  "name": "Youtube Speed Controller",
  "version": "1.0",
  "description": "Control youtube speed",
  "manifest_version": 2,
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "webNavigation",
    "activeTab",
    "tabs",
    "http://*/",
    "https://*/"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/icon-16.png",
      "32": "images/icon-32.png"
    }
  },
  "applications": {
    "gecko": {
      "id": "yt-speed-controller@thecoffeecoders.com"
    }
  }
}