Examine source code of GitZip for github

{
  "manifest_version": 2,
  "name": "GitZip for github",
  "description": "It can make the sub-directories and files of github repository as zip and download it",
  "version": "1.0.4",
  "icons": {
    "128": "images/icon-128px.png"
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "options_page": "options.html",
  "background": {
    "scripts": [
      "js/background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "storage",
    "contextMenus",
    "https://api.github.com/*",
    "*://github.com/*",
    "*://kinolien.github.io/gitzip/*",
    "*://gitzip.org/gettoken/success"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://github.com/*"
      ],
      "js": [
        "js/content/jszip.min.js",
        "js/content/FileSaver.min.js",
        "js/content/main.js"
      ],
      "css": [
        "css/main.css"
      ]
    },
    {
      "matches": [
        "*://kinolien.github.io/gitzip/*"
      ],
      "js": [
        "js/content/keysync.js"
      ]
    },
    {
      "matches": [
        "*://gitzip.org/gettoken/success"
      ],
      "js": [
        "js/content/autosave.js"
      ]
    }
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'; worker-src 'self'",
  "browser_specific_settings": {
    "gecko": {
      "id": "{c668188a-f573-40af-a971-5f0e73a8d432}"
    }
  }
}