Examine source code of silent-twitter

{
  "manifest_version": 2,
  "name": "silent-twitter",
  "version": "0.2",
  "description": "mute what's happing and who to follow from twitter.",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.twitter.com/*"
      ],
      "css": [
        "silent.css"
      ]
    }
  ]
}