We currently use RenderWidgetHostImpl::StartHangMonitorTimeout for several types of unresponsiveness timers: input events (30 seconds), beforeunload (1 second), and close (1 second).  There's a complex set of state checks to decide how to react when the timer expires and how it's set, involving IsWaitingForUnloadACK() and is_waiting_for_beforeunload_ack().

This approach is fragile and risks showing the hung renderer dialog after only 1 second if any state is incorrect.  It was also the source of several bugs when originally getting the timer code to work for cross-process beforeunload/unload handlers.

We should switch to using separate timers for beforeunload and close, the way we've done for swapout_event_monitor_timeout_ on RenderFrameHostImpl.