Examine source code of Username Lookup Assistant

{
  "manifest_version": 2,
  "name": "Username Lookup Assistant",
  "version": "0.1.0",
  "description": "",
  "icons": {
    "64": "user.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "contextMenus",
    "tabs",
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{f5c9bfb4-4eb3-4990-a305-159152f20638}"
    }
  }
}