Examine source code of GitHub Widener

{
  "manifest_version": 2,
  "name": "GitHub Widener",
  "version": "0.5",
  "description": "Expands the GitHub code pane to the full window width.",
  "homepage_url": "https://github.com/danstewart/github-widener",
  "icons": {
    "48": "icons/gh-widener-48.png"
  },
  "permissions": [
    "history",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/gh-widener-48.png",
      "32": "icons/gh-widener-48.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://github.com/*",
        "*://gist.github.com/*"
      ],
      "js": [
        "widener.js"
      ]
    }
  ]
}