If it says Google cloud printer offline and you have no clue why then you are at the right place. This issue usually takes place when there is a communication problem between the system and the printer. If your printer is not connected to a power source or internet connection then you will eventually face this issue.
This could also take place if the printer has not been configured in a correct manner or if the printer is not Google cloud ready. You should make sure whether the printer has been disconnected unknowingly or not and if it has then connect it again to solve this blunder.
These mistakes do seem to be petty but they are way too common and just by paying close attention you can get yourself out of Google cloud printer offline situation in no time.