The use of cruise missiles is unnecessary. The number of suitable targets will be limited and these can be left to Russia.
Reconnaissance is the responsibility of the alliance of Syria, Iraq, Iran and Russia, coordinated in Baghdad, and a Chinese contribution is here too unnecessary.
The Iranian air force consist mostly of older aircraft and when the pressure is raised in Iraq in response to an advance by the Syrian army against ISIL in that country Iran might want to receive support from Russia or China. If US feel themselves pushed out by Russia from two sides they might look for an incident to cause more trouble while that might be less likely if the support comes from China.
As it is Russia even now has intensive diplomatic interactions with Saudi Arabia. Seeing US pushed out will not cause Saudi Arabia to diminish diplomatic relations with China. To the contrary these relations become more important as it should be competing with China's relations with Iran.
If you look at how Beijing decides with its military.. I don't think they are interested in such a scale of military adventurism.
China participated in anti-piracy operations in Somalia not just to protect its own shipping and international ships but also with the benefit of gaining experience operating far ashore amd interacting with other navies.
If China will mount such an operation in Iraq and Syria.. There is not much to gain in just flying jets and bombing targets, PLAAF can do that in China. The ISIS nor Syrian rebels does not have an airforce for an air to air combat.
Testing and deplyment of China's new recon aircraft and drones would interest Beijing more. Infact even firing and testing its cruise missiles in actual use. Deployment of new Tanks and Armored vehicles would also suits Beijing's interests.
Turkey and Russia has good relations prior to Russian intervention in Syria. But it deteriorated.
If China and Iran cooperates in such scale. It will surely displease Saudi Arabia, UAE, Israel, and even its staunch ally and friend Pakistan. Remember Pakistan is a Sunni Muslim country.
Such cooperation with Iran will be harmful to China.