I am just reading with the "Livemargin Reader"
https://chrome.google.com/webstore/s...e-ntp-launcher
which seems to be based on Readium but seems better designed.
I think it's early days for these things.
I have a folder "CalibreLibrary" on my GoogleDrive to which Calibre directly exported its library. Both Readium and Livemargin can grab books from there.