Examine source code of Hide Twitter Sidebars

{
  "manifest_version": 2,
  "name": "Hide Twitter Sidebars",
  "version": "1.5",
  "description": "Hides Twitter sidebars.",
  "icons": {
    "48": "assets/twitter48.png",
    "128": "assets/twitter128.png",
    "512": "assets/twitter512.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://twitter.com/*"
      ],
      "js": [
        "hideSidebar.js"
      ],
      "run_at": "document_start"
    }
  ]
}