Examine source code of CRX Extractor

{
  "name": "CRX Extractor",
  "version": "1.0.1",
  "manifest_version": 2,
  "description": "Extract CRX Files directly as crx or zip file depending upon your choice",
  "permissions": [
    "downloads",
    "contextMenus",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "16": "16.png",
    "48": "48.png",
    "128": "128.png"
  },
  "browser_action": {
    "default_icon": "128.png",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e3afb4f2-5f63-42c5-ac37-352f81509490}"
    }
  }
}