Examine source code of GetSum

{
  "name": "__MSG_extName__",
  "version": "2.0.6",
  "manifest_version": 2,
  "description": "__MSG_extDesc__",
  "icons": {
    "16": "icon_16.png",
    "128": "icon_128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "jquery-3.4.1.min.js",
        "content.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "web_accessible_resources": [
    "modal.html"
  ],
  "default_locale": "en",
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "permissions": [
    "contextMenus",
    "downloads",
    "downloads.open",
    "<all_urls>"
  ]
}