Examine source code of CSS Reloader

{
  "manifest_version": 2,
  "name": "CSS Reloader",
  "version": "1.2.1resigned1",
  "description": "CSS Reloader is a browser extension which allows developers to reload CSS without reloading the page itself.",
  "options_ui": {
    "page": "options.htm"
  },
  "background": {
    "page": "background.htm"
  },
  "permissions": [
    "http://*/*",
    "https://*/*",
    "contextMenus",
    "tabs"
  ],
  "icons": {
    "16": "icons/icon_16.png",
    "48": "icons/icon_48.png",
    "128": "icons/icon_128.png",
    "256": "icons/icon_256.png"
  },
  "content_scripts": [
    {
      "all_frames": true,
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "browser-polyfill.min.js",
        "cssreloader.content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "cssreloader@kenneth.io"
    }
  }
}