Maintain the current renderer_hang_count in Stability.Counts.

content/browser/frame_host/render_frame_host_impl.cc

Index: content/browser/frame_host/render_frame_host_impl.cc
diff --git a/content/browser/frame_host/render_frame_host_impl.cc b/content/browser/frame_host/render_frame_host_impl.cc
index b802e463954c6addd214e1f540079774f5ff6cb2..3e6ecb7363350d212081f4eff7b5a98df55045c5 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -73,6 +73,8 @@
 #include "content/public/browser/browser_plugin_guest_manager.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/content_browser_client.h"
+#include "content/public/browser/notification_service.h"
+#include "content/public/browser/notification_types.h"
 #include "content/public/browser/permission_manager.h"
 #include "content/public/browser/permission_type.h"
 #include "content/public/browser/render_process_host.h"
@@ -3461,6 +3463,12 @@ RenderFrameHostImpl::TakeNavigationHandleForCommit(
 }
 
 void RenderFrameHostImpl::BeforeUnloadTimeout() {
+  // Temporarily fire "hung" events to keep the renderer_hang_count from
+  // Stability.Counts stable.
+  NotificationService::current()->Notify(NOTIFICATION_RENDER_WIDGET_HOST_HANG,
+                                         Source<RenderWidgetHost>(nullptr),
+                                         NotificationService::NoDetails());
+
   if (render_view_host_->GetDelegate()->ShouldIgnoreUnresponsiveRenderer())
     return;