Examine source code of GitHub Default Tab Size

{
  "name": "GitHub Default Tab Size",
  "version": "1.0.4",
  "icons": {
    "256": "icon.png"
  },
  "description": "Make tab indented code more readable by allowing you to set a default tab size",
  "homepage_url": "https://github.com/forivall/github-custom-tab-size",
  "manifest_version": 2,
  "minimum_chrome_version": "36",
  "browser_action": {
    "default_popup": "src/popup.html"
  },
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "run_at": "document_start",
      "matches": [
        "https://github.com/*/*",
        "https://gist.github.com/*/*"
      ],
      "js": [
        "src/content.js"
      ]
    }
  ],
  "applications": {
    "gecko": {
      "id": "jcjfkmdkcaopkioccnpbhiemfcmpnghe@forivall"
    }
  }
}