Examine source code of SendCookies

{
  "description": "Send cookies from website to another device.",
  "manifest_version": 2,
  "name": "SendCookies",
  "version": "1.0.0",
  "author": "sh4ka",
  "icons": {
    "48": "icons/icon2.svg"
  },
  "browser_action": {
    "browser_style": false,
    "default_icon": {
      "16": "icons/icon2.svg",
      "32": "icons/icon2.svg",
      "48": "icons/icon2.svg",
      "64": "icons/icon2.svg",
      "128": "icons/icon2.svg"
    },
    "default_popup": "popup.html",
    "default_title": "SendCookies"
  },
  "background": {
    "scripts": [
      "bg.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "sh4ka@sendcookies"
    }
  },
  "permissions": [
    "cookies",
    "<all_urls>",
    "storage"
  ]
}