The Chinese already have a small presence in syria with advisers attached to the Russian mission. They also are literally giving weapons to Assad and Hezbollah fighters there. The Chinese will likely increase their assistance to the Russian mission in syria; the logistics train and presence is already established.
The Chinese also has agreements in place with Russia to join at a later date; this gives the Chinese government the pretext it needed to enter. Chinese J-15 fighters are already in the region.