Examine source code of Wide GitHub

{
  "manifest_version": 2,
  "name": "Wide GitHub",
  "description": "Change all GitHub repository and gist pages to be full width and dynamically sized.",
  "version": "1.7.4",
  "icons": {
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a29c89d0-8d34-47c1-8c30-6e4ade95bd1a}"
    }
  },
  "browser_action": {
    "default_icon": "icons/icon.png",
    "default_title": "Toggle Wide GitHub"
  },
  "content_scripts": [
    {
      "matches": [
        "https://github.com/*",
        "https://gist.github.com/*"
      ],
      "css": [
        "wide-github.css"
      ],
      "js": [
        "wide-github-toggle.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}