Examine source code of Always Following Tab

{
  "manifest_version": 2,
  "name": "Always Following",
  "version": "1.0",
  "description": "Keep twitter timeline always on Following tab.",
  "content_scripts": [
    {
      "matches": [
        "*://*.twitter.com/*"
      ],
      "js": [
        "viewer.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{4022e5ab-c323-4f3b-9231-cb2bc26fe934}"
    }
  }
}