Examine source code of Power+

{
  "manifest_version": 3,
  "name": "Power+",
  "description": "A better UI for Canvas LMS",
  "version": "3.3.1",
  "content_scripts": [
    {
      "run_at": "document_start",
      "matches": [
        "https://*/*"
      ],
      "js": [
        "injector.js"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "loader.js"
      ],
      "matches": [
        "*://*/*"
      ]
    }
  ],
  "icons": {
    "16": "16.png",
    "32": "32.png",
    "48": "48.png",
    "128": "128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{45a61d8d-6de3-4718-b422-a8a777f2d8aa}"
    }
  }
}