Examine source code of Firedown

{
  "name": "Firedown",
  "short_name": "Markdown Editor",
  "version": "1.5.1",
  "description": "Take down notes 🗒️, save reminders ⏰, paste links 🔗, create checklists ☑️ all using markdown... directly in your browser!",
  "manifest_version": 2,
  "permissions": [
    "storage"
  ],
  "applications": {
    "gecko": {
      "id": "@markdowntab",
      "strict_min_version": "57.0"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/icon16.png",
      "38": "icons/icon128.png"
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  }
}