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

content/public/test/mock_render_process_host.cc

Index: content/public/test/mock_render_process_host.cc
diff --git a/content/public/test/mock_render_process_host.cc b/content/public/test/mock_render_process_host.cc
index 1fc3eab203cc5a604ae747dc599092fe4f621cd7..33589eeef787b1c85d0132a5f2ccb12d72ac5a83 100644
--- a/content/public/test/mock_render_process_host.cc
+++ b/content/public/test/mock_render_process_host.cc
@@ -12,6 +12,7 @@
 #include "content/browser/renderer_host/render_view_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/common/child_process_host_impl.h"
+#include "content/public/browser/global_request_id.h"
 #include "content/public/browser/render_widget_host_iterator.h"
 #include "content/public/browser/storage_partition.h"
 
@@ -259,6 +260,9 @@ void MockRenderProcessHost::DisableAecDump() {
 }
 #endif
 
+void MockRenderProcessHost::ResumeDeferredNavigation(
+    const GlobalRequestID& request_id) {}
+
 bool MockRenderProcessHost::OnMessageReceived(const IPC::Message& msg) {
   IPC::Listener* listener = listeners_.Lookup(msg.routing_id());
   if (listener)