Examine source code of FocusTube

{
  "manifest_version": 2,
  "name": "focustube",
  "version": "2.1resigned1",
  "description": "Watch your YouTube videos while scrolling through the comment section",
  "icons": {
    "48": "icons/focustube-48.png"
  },
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icons/focustube-48.png",
    "default_title": "FocusTube"
  },
  "background": {
    "scripts": [
      "index.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{ae4801b4-de43-4cea-8dcd-07155bcc739e}"
    }
  }
}