NetworkProcess does not always terminate on macOS. The reason for this is that NetworkProcess can suspend in the middle of termination. NetworkProcess drops its "m_backgroundActivityToPreventSuspension" as part of the NetworkProcessProxy destructor, which allows it to suspend. Then, the AuxiliaryProcessProxy destructor runs and starts termination by invalidating via IPC::Connection::invalidate. However, the remote side of the connection invalidation in NetworkProcess (in NetworkProcess::didClose) might never run if the process is already suspended, which then leaves the process in a permanently suspended state. To fix this, we should use XPCConnectionTerminationWatchdog to resume the network process and allow it to gracefully exit, or forcefully terminate it after 30 seconds.