Xi and Trump are in close contact and the Chinese President will let his US counterpart know how realistic the prospects are for a future North Korean-US summit.
That depends.
Could be Xi and Kim compared notes. Yes.
Could be Xi will let Trump know how realistic the prospects for a future North Korea-US summit are.
But it could also be, that China and North Korea coordinated on strategy (against) America.
Or both, China will update America. And also they met with Kim about anti-American strategy.
I myself, think that is most likely.