fix flow type for CacheManager
fix flow type for CacheManager

Summary: Not sure why flow didn't catch this on www while it did on fbobjc. Anyway, fixing this upstream now too.

Reviewed By: @yuzhi

Differential Revision: D2541608

fb-gh-sync-id: a667d8f2a5fdd1a854f7913d775f8d5b3ddb9578

voideanvalue/relay,venepe/relay,josephsavona/relay,facebook/relay,facebook/relay,apalm/relay,NevilleS/relay,facebook/relay,kassens/relay,forter/generic-relay,zpao/relay,facebook/relay,rosskevin/relay,xuorig/relay,cpojer/relay,michaelchum/relay,yungsters/relay,iamchenxin/relay,xuorig/relay,mroch/relay,wincent/relay,wincent/relay,kassens/relay,voideanvalue/relay,andimarek/generic-relay,gabelevi/relay,atxwebs/relay,mroch/relay,chentsulin/relay,heracek/relay,zpao/relay,facebook/relay,josephsavona/relay,heracek/relay,atxwebs/relay,chirag04/relay,xuorig/relay,wincent/relay,benjaminogles/relay,atxwebs/relay,andimarek/generic-relay,michaelchum/relay,voideanvalue/relay,mroch/relay,NevilleS/relay,chentsulin/relay,chirag04/relay,dbslone/relay,wincent/relay,andimarek/generic-relay,freiksenet/relay,cesarandreu/relay,voideanvalue/relay,michaelchum/relay,cpojer/relay,chentsulin/relay,iamchenxin/relay,benjaminogles/relay,venepe/relay,freiksenet/relay,xuorig/relay,dbslone/relay,rosskevin/relay,cesarandreu/relay,xuorig/relay,facebook/relay,Aweary/relay,wincent/relay,kassens/relay,josephsavona/relay,NevilleS/relay,cpojer/relay,heracek/relay,cesarandreu/relay,venepe/relay,gabelevi/relay,xuorig/relay,kassens/relay,yungsters/relay,iamchenxin/relay,freiksenet/relay,yungsters/relay,kassens/relay,chirag04/relay,apalm/relay,Aweary/relay,gabelevi/relay,benjaminogles/relay,kassens/relay,iamchenxin/relay,voideanvalue/relay,cpojer/relay,Aweary/relay,zpao/relay,apalm/relay,atxwebs/relay,wincent/relay,voideanvalue/relay