Examine source code of Reddit Image Expander

{
  "manifest_version": 2,
  "name": "Reddit Image Expander",
  "version": "3.1",
  "description": "Expand images on Reddit by hovering over the thumbnail.",
  "permissions": [
    "webRequest",
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.reddit.com/*"
      ],
      "js": [
        "index.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{59e08757-15c0-412c-84fe-b107fb4951b0}"
    }
  }
}