The MacOS system Touch ID prompt shows up on top of the Chrome fingerprint prompt. It looks odd. 

The Chrome fingerprint prompt can be interacted with if you move the system prompt out of the way. This lets the user select a different transport if they wish. It's not intuitive and users probably won't realize they can do this.

We should implement a retry screen so that we can hide the Chrome dialog. Then pressing 'cancel' on the system prompt will go back to Chrome UI, which will ask the user to retry with another modality.