Examine source code of Google Discovery

{
  "manifest_version": 2,
  "name": "GD Notícias",
  "description": "A extensão oficial do GD!",
  "version": "1.3",
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    }
  },
  "permissions": [
    "storage",
    "https://gd.eurisko.com.br/*"
  ],
  "background": {
    "scripts": [
      "popup.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{01407680-86e4-47c8-b14d-178408edc9ac}"
    }
  }
}