Examine source code of Canonical

{
  "manifest_version": 2,
  "name": "Canonical",
  "version": "1.4",
  "description": "Allows you to quickly navigate to or copy the canonical version of the URL you're on, if available.",
  "author": "Web Guy",
  "homepage_url": "https://github.com/webguyio/canonical",
  "icons": {
    "16": "icons/blue/16.png",
    "32": "icons/blue/32.png",
    "96": "icons/blue/96.png"
  },
  "permissions": [
    "activeTab",
    "clipboardWrite",
    "contextMenus"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "run_at": "document_start",
      "js": [
        "canonical.js"
      ]
    }
  ],
  "background": {
    "persistent": false,
    "scripts": [
      "background.js"
    ]
  },
  "page_action": {},
  "browser_specific_settings": {
    "gecko": {
      "id": "{f55a3563-7902-4140-bd77-747edd3b57eb}",
      "strict_min_version": "79.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}