I do believe that majority of mining farm is located in China but I doubt that majority of it is owned by chinese. The reason for this is that if ever the majority of hashes is owned by Chinese then the increase in blocksize will never had problem in getting the percentage it wanted for hardforking bitcoin. But it seems it isn't controlled by chinese.
Majority of mining farms are located in China... that is a fact. My original concern was that with majority control the Chinese would be able to manipulate the block-chain technology, i.e reverse transactions / deny transactions at their own will. However it appears that is only the case for Ethereum. In regards to Bitcoin and the Chinese, whilst majority of all Bitcoin being mined comes out of China, not all of the mining groups are working together - so they may as well be spread out around the world, it makes no difference.