Don't you have anything better to do?

manifest.json

{
  "update_url": "http://clients2.google.com/service/update2/crx",
  "name": "Don't you have anything better to do?",
  "version": "0.2",
  "manifest_version": 2,
  "description": "A simple site blocker.",
  "browser_action": {
    "default_icon": "dontyou.png",
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "background": {
    "scripts": [
      "dontyou.js"
    ]
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "storage",
    "tabs",
    "<all_urls>"
  ]
}