Transport helicopters are a completely different matter from submarines and destroyers. Additionally, I was under the impression that the helicopter plant in chengdu is not the only one. I can see that Russia would like to expand its military supply complex, perhaps in a different, low-cost country, but to move its entire military-industrial production base to foreign territory would be a strategic blunder unlike any other, no matter how good relations they have with each other. The US wouldn't even let Britain have access to the most advanced technology on the JSF, even though they have perhaps the closest relationship of any two developed countries in the world today.
Russia and China I think IS in a strategic partnership (but I guess there are different definitions of this), most importantly through the Shanghai Cooperation Organization. The trouble in the last few years has been that Russia's ambitions have grown exponentionally. While China still tries to calm the west, its friend to the north is moving its chess pieces to counter NATO (and makes this known too). We have yet to see if Russia and China is in a short period of pragmatic partnership now, or if China gets ambitious enough to side strongly with Russia.
Yet I feel the discussion of a Russia-China partnership is somehow off-topic, so I'll shut up now.