Examine source code of WPlace decor replacer

{
  "manifest_version": 3,
  "name": "WPlace Avatar Replacer",
  "version": "1.3",
  "description": "Replaces every <img> with src starting with 'https://files.wplace.live/img/uploads/' with 'https://wplacepixels.web.app/sprites/pokeavatar.png' on all pages.",
  "permissions": [
    "scripting",
    "storage",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "host_permissions": [
    "<all_urls>",
    "https://wplacepixels-default-rtdb.europe-west1.firebasedatabase.app/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "16": "icon.png",
    "32": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "frenxys@github.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}