Revert of Move beforeunload hang timer duties to its own timer.

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index ead180c02ce45052c963e15b4e5780a0e4eead62..e0540017123d77acb24a7e675abe5d4137b8b1be 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -2106,15 +2106,14 @@
 
 void RenderWidgetHostImpl::IncrementInFlightEventCount(
     blink::WebInputEvent::Type event_type) {
-  ++in_flight_event_count_;
+  increment_in_flight_event_count();
   if (!is_hidden_)
     StartHangMonitorTimeout(hung_renderer_delay_, event_type);
 }
 
 void RenderWidgetHostImpl::DecrementInFlightEventCount(
     InputEventAckSource ack_source) {
-  --in_flight_event_count_;
-  if (in_flight_event_count_ <= 0) {
+  if (decrement_in_flight_event_count() <= 0) {
     // Cancel pending hung renderer checks since the renderer is responsive.
     StopHangMonitorTimeout();
   } else {