Examine source code of Roll20 DnD Sheet678

{
  "name": "Roll20 DnD Sheet",
  "manifest_version": 2,
  "icons": {
    "128": "icon.png"
  },
  "permissions": [
    "*://app.roll20.net/editor/",
    "*://app.roll20.net/editor",
    "*://app.roll20.net/editor?*",
    "*://app.roll20.net/editor#*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://app.roll20.net/editor",
        "https://app.roll20.net/editor/",
        "https://app.roll20.net/editor/#*",
        "https://app.roll20.net/editor#*",
        "https://app.roll20.net/editor/?*",
        "https://app.roll20.net/editor?*"
      ],
      "js": [
        "injector.js"
      ],
      "run_at": "document_start"
    }
  ],
  "web_accessible_resources": [
    "wshook.js",
    "bundle.js",
    "bundle.css"
  ],
  "version": "1.0.0",
  "browser_specific_settings": {
    "gecko": {
      "id": "{cca3d378-f35b-46fb-b5bd-99427eb8d545}"
    }
  }
}