Examine source code of WebStats

{
  "manifest_version": 2,
  "name": "WebStats",
  "description": "Show internet usage",
  "version": "2.0.0",
  "icons": {
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "webRequest",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "build/background.js"
    ]
  },
  "browser_action": {
    "browser_style": true,
    "default_popup": "popup.html"
  },
  "options_ui": {
    "page": "index.html",
    "open_in_tab": true
  },
  "default_locale": "en"
}