Examine source code of IIchan big reply

{
  "manifest_version": 2,
  "name": "IIchan-big-reply",
  "version": "1.0",
  "description": "Iichan extension that enlarges a user's reply in a thread to the full width of the screen.",
  "icons": {
    "48": "icons/border-48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "iichan-big-reply@iichan.hk"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://iichan.hk/*"
      ],
      "js": [
        "bigReply.js"
      ]
    }
  ],
  "browser_action": {
    "default_popup": "popup/popup.html",
    "default_title": "IIchan big reply"
  },
  "permissions": [
    "activeTab"
  ]
}