Google Chrome	51.0.2704.26 (Official Build) dev (32-bit)
Revision	0
Platform	8172.12.0 (Official Build) dev-channel veyron_speedy

What steps will reproduce the problem?
(1) Open Files app Drive folder
(2) Right click on a large file and enable 'Available offline'
(3) Syncing starts. Click 'x' button on the syncing message
(4) Syncing is cancelled
(5) Right click on the file

What do you see instead?
'Available offline' option is still checked.