Examine source code of 4Chan Image Expand

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "manifest_version": 2,
  "name": "4chan Image Expander & Saver",
  "description": "Expands all images & webm's in a thread with the click of a button. Once expanded, you can choose to save all images into a folder.",
  "version": "0.5resigned1",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "http://www.4chan.org/*",
        "https://www.4chan.org/*",
        "http://boards.4chan.org/*",
        "https://boards.4chan.org/*"
      ],
      "js": [
        "jquery-2.1.3.min.js",
        "4c.js"
      ]
    }
  ],
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{3859d492-cbb8-4ce1-a1c2-d9394ea829df}"
    }
  }
}