You can access the locally synchronized Drive folder (used by the rest of ChromeOS) from chroot in this directory:
/ var / host / media / fuse / drivefs- [unique identifier] / root /
Please note that the unique identifier is different on each computer (or perhaps in every Google account?) - you will need to find it yourself.
This can also be obtained from the ChromeOS shell here:
/ media / fuse / drivefs- [unique identifier] / root /
source share