When the WebContent wants to complete a task in the background we take a process assertion on the child process, and also need to prevent the UI process from suspending. (see: https://bugs.webkit.org/show_bug.cgi?id=134563 ) However for the NetworkProcess we always just hold a process assertion, and don't want this to interfere with UIApp suspension.
Created attachment 234385 [details] Fix
Transmitting file data ....... Committed revision 170785.