Have the unload event execute in background on cross-site navigations

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 a41c0510677c46220750980d0ee54cd9941251db..977b6c51da63a2001759b28927f8c46d821a5eba 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -190,4 +190,8 @@ void RenderFrameHostImpl::OnSwappedOut(bool timed_out) {
   frame_tree_node_->render_manager()->SwappedOutFrame(this);
 }
 
+void RenderFrameHostImpl::SetPendingShutdown(const base::Closure& on_swap_out) {
+  render_view_host_->SetPendingShutdown(on_swap_out);
+}
+
 }  // namespace content