Issue AboutToNavigateRenderFrame notification after beforeunload handling.

content/browser/frame_host/render_frame_host_manager.cc

Index: content/browser/frame_host/render_frame_host_manager.cc
diff --git a/content/browser/frame_host/render_frame_host_manager.cc b/content/browser/frame_host/render_frame_host_manager.cc
index bc8a487c3db31f79e03dd1a36856969126ff648e..9789b75ff33701d28e1909bc315057a6be400e73 100644
--- a/content/browser/frame_host/render_frame_host_manager.cc
+++ b/content/browser/frame_host/render_frame_host_manager.cc
@@ -556,6 +556,12 @@ void RenderFrameHostManager::OnBeforeUnloadACK(
       // is ok to do nothing here.
       if (pending_render_frame_host_ &&
           pending_render_frame_host_->are_navigations_suspended()) {
+        NavigatorDelegate* navigator_delegate =
+            frame_tree_node_->navigator()->GetDelegate();
+        if (navigator_delegate) {
+          navigator_delegate->AboutToNavigateRenderFrame(
+              render_frame_host_.get(), pending_render_frame_host_.get());
+        }
         pending_render_frame_host_->SetNavigationsSuspended(false,
                                                             proceed_time);
       }