Examine source code of Open in Containers

{
  "manifest_version": 2,
  "name": "Open in Containers",
  "version": "0.1.0",
  "incognito": "not_allowed",
  "description": "Adds a context menu item to open link in all containers at once.",
  "applications": {
    "gecko": {
      "id": "@open-in-containers",
      "strict_min_version": "67.0"
    }
  },
  "permissions": [
    "activeTab",
    "bookmarks",
    "cookies",
    "contextMenus",
    "contextualIdentities",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}