Disable the hang dialog detector when showModalDialog is running.

content/browser/renderer_host/render_widget_host_impl.h

Index: content/browser/renderer_host/render_widget_host_impl.h
diff --git a/content/browser/renderer_host/render_widget_host_impl.h b/content/browser/renderer_host/render_widget_host_impl.h
index 222ac68e3b084e7b79f665bdcd5ebc81743ca5f4..5a2ee7e4364a73965e06f7968400dd8234b9f41e 100644
--- a/content/browser/renderer_host/render_widget_host_impl.h
+++ b/content/browser/renderer_host/render_widget_host_impl.h
@@ -429,6 +429,11 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   void SetShouldAutoResize(bool enable);
 
  protected:
+  // Expose increment/decrement of the in-flight event count, so
+  // RenderViewHostImpl can account for in-flight beforeunload/unload events.
+  int increment_in_flight_event_count() { return ++in_flight_event_count_; }
+  int decrement_in_flight_event_count() { return --in_flight_event_count_; }
+
   // The View associated with the RenderViewHost. The lifetime of this object
   // is associated with the lifetime of the Render process. If the Renderer
   // crashes, its View is destroyed and this pointer becomes NULL, even though