Examine source code of modekun

{
  "manifest_version": 2,
  "applications": {
    "gecko": {
      "id": "modekun@tjmtmmnk"
    }
  },
  "name": "modekun",
  "description": "moderate live chat",
  "version": "1.0.1",
  "content_security_policy": "script-src 'self'; object-src 'none'",
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "64": "icon64.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*",
        "https://www.mildom.com/*",
        "https://www.twitch.tv/*"
      ],
      "js": [
        "js/content_script.js"
      ],
      "run_at": "document_start"
    }
  ],
  "permissions": [
    "activeTab",
    "storage"
  ],
  "web_accessible_resources": [
    "kuromoji/dict/*",
    "js/worker.js"
  ],
  "default_locale": "ja"
}