Examine source code of HTTP Server header Spy

{
  "description": "all info about the server",
  "manifest_version": 2,
  "name": "Server Spy",
  "version": "2.2",
  "homepage_url": "https://github.com/dw5/ServerSpy-Extension",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "96": "icons/icon-48@2x.png",
    "128": "icons/icon-128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "tabs",
    "http://*/*",
    "https://*/*",
    "webRequest"
  ],
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_title": "spy",
    "default_popup": "popup/server_detail.html"
  }
}