Use of drawWindow method from CanvasRenderingContext2D is deprecated. Use tabs.captureTab extensions API instead https://developer.mozilla.org/docs/Mozilla/Add-ons/WebExtensions/API/tabs/captureTab
El uso del método drawWindow de CanvasRenderingContext2D está obsoleto. Usa la API de extensiones tabs.captureTab en su lugar https://developer.mozilla.org/docs/Mozilla/Add-ons/WebExtensions/API/tabs/captureTab