Examine source code of Tab Previewer Plus

{
  "manifest_version": 2,
  "version": "0.3.1",
  "name": "Popup Tab",
  "description": "Convert a tab into a popup and vice versa",
  "author": "eight",
  "homepage_url": "https://github.com/eight04/popup-tab",
  "permissions": [
    "contextMenus",
    "activeTab",
    "storage"
  ],
  "background": {
    "scripts": []
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "popup-tab@eight05.blogspot.com"
    }
  },
  "commands": {
    "popupTab": {
      "description": "Popup tab/merge popup"
    }
  }
}