The cookie-handling code lives under Source/WebKit2/WebProcess/Cookies, but will run in the network process unless the network process is disabled. This should probably be moved to Shared.
(In reply to Michael Catanzaro from comment #0) > The cookie-handling code lives under Source/WebKit2/WebProcess/Cookies, but > will run in the network process unless the network process is disabled. This > should probably be moved to Shared. As of today (January 17th, 2019) the cookies code is under “Source/WebKit/NetworkProcess/Cookies/”, so I reckon this bug can be closed :)