Firefox add-ons have a different namespace and some additional APIs that Blink does not support. See https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/We

Firefox add-ons have a different namespace and some additional APIs that Blink does not support. See https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Chrome_incompatibilities https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/Web... and https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Differences_between_API_implementations https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/Web...