Examine source code of New Container Tab

{
  "author": "Karim Rahal",
  "name": "New Container Tab",
  "description": "Quickly open a new tab in any Firefox container. Shortcut: Ctrl+Shift+Comma.",
  "icons": {
    "96": "img/icon-96.png"
  },
  "manifest_version": 2,
  "version": "1.12",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "img/icon-96.png",
    "default_popup": "popup/container-selection.html"
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Shift+Ctrl+Comma"
      }
    }
  },
  "options_ui": {
    "page": "options/options.html",
    "browser_style": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{2998d6c4-c705-46ee-a4c5-6ba91600bfda}"
    }
  },
  "permissions": [
    "storage",
    "cookies",
    "contextualIdentities"
  ]
}