WebContents could be blocked after pending cross-site navigation is canceled.

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 dc1393cb65da8e3bbe1ed4a689f196bc7e20f52c..a884b43f87ac15879c97fc8991d5b8a913928572 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -528,8 +528,15 @@ void RenderFrameHostImpl::OnBeforeUnloadACK(
   // If this renderer navigated while the beforeunload request was in flight, we
   // may have cleared this state in OnNavigate, in which case we can ignore
   // this message.
+  // However renderer might also be swapped out but we still want to proceed
+  // with navigation, otherwise it would block whole web_contents. This can
+  // happen when pending cross-site navigation is canceled by second one just
+  // before OnNavigate, current (loaded) RVH is waiting for commit but second
+  // navigation is started from the beginning.
   if (!render_view_host_->is_waiting_for_beforeunload_ack_ ||
-      render_view_host_->rvh_state_ != RenderViewHostImpl::STATE_DEFAULT) {
+      (render_view_host_->rvh_state_ != RenderViewHostImpl::STATE_DEFAULT &&
+       render_view_host_->rvh_state_ !=
+           RenderViewHostImpl::STATE_WAITING_FOR_COMMIT)) {
     return;
   }