Examine source code of ManiFans

{
  "name": "ManiFans",
  "version": "1.2.1",
  "description": "Browser extension for Manifold Markets, displaying digital flair on users that hold large positions in permanent markets/stocks.",
  "manifest_version": 2,
  "icons": {
    "128": "icons/icon128.png"
  },
  "browser_action": {
    "default_icon": {
      "128": "icons/icon128.png"
    },
    "default_title": "ManiFans",
    "default_popup": "popup/popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "manifans.extension@gmail.com",
      "strict_min_version": "57.0"
    }
  },
  "permissions": [
    "storage",
    "activeTab",
    "https://manifold.markets/*",
    "https://manifold.markets/api/v0/markets"
  ],
  "background": {
    "scripts": [
      "background/background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "https://manifold.markets/*"
      ],
      "css": [
        "content/content.css"
      ],
      "js": [
        "content/content.js"
      ],
      "run_at": "document_end"
    }
  ]
}