This solution still isn't technically correct because it could take more
than 40 seconds to download a file. I could simply not revoke any files,
but then users would run into issues once they have saved a cumulative
total of over 500MB (
https://bugs.chromium.org/p/chromium/issues/detail?id=375297 )
Complain to @sicking and @arunranga for creating and standardizing an
incomplete revocation API.