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

content/browser/frame_host/render_frame_host_impl.h

Index: content/browser/frame_host/render_frame_host_impl.h
diff --git a/content/browser/frame_host/render_frame_host_impl.h b/content/browser/frame_host/render_frame_host_impl.h
index 64864cb10789da9e49a2007ac7a7549bc02630ff..65828103cabc4be888d2097ccb5f3b149155944b 100644
--- a/content/browser/frame_host/render_frame_host_impl.h
+++ b/content/browser/frame_host/render_frame_host_impl.h
@@ -7,6 +7,7 @@
 
 #include <string>
 
+#include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/render_frame_host.h"
@@ -83,6 +84,10 @@ class CONTENT_EXPORT RenderFrameHostImpl : public RenderFrameHost {
     is_swapped_out_ = is_swapped_out;
   }
 
+  // Sets the RVH for |this| as pending shutdown. |on_swap_out| will be called
+  // when the SwapOutACK is received.
+  void SetPendingShutdown(const base::Closure& on_swap_out);
+
  protected:
   friend class RenderFrameHostFactory;