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 de la drawWindow desde CanvasRenderingContext2D es obsoleto. Usar las pestañas.captureTab extensions API en lugar de https://developer.mozilla.org/docs/Mozilla/Add-ons/WebExtensions/API/tabs/captureTab