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

content/browser/renderer_host/render_widget_host_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 
 #include <math.h>
 
 #include <set>
 #include <tuple>
@@ skipping 2088 matching lines @@
       delegate_->OnUserInteraction(this, event.type());
     }
   }
 
   return view_ ? view_->FilterInputEvent(event)
                : INPUT_EVENT_ACK_STATE_NOT_CONSUMED;
 }
 
 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 {
     // Only restart the hang monitor timer if we got a response from the
     // main thread.
     if (ack_source == InputEventAckSource::MAIN_THREAD)
       RestartHangMonitorTimeoutIfNecessary();
   }
 }
 
@@ skipping 420 matching lines @@
     // different from the receiver's.
     file_system_file.url =
         GURL(storage::GetIsolatedFileSystemRootURIString(
                  file_system_url.origin(), filesystem_id, std::string())
                  .append(register_name));
     file_system_file.filesystem_id = filesystem_id;
   }
 }
 
 }  // namespace content