Support window.opener after a process swap.

content/renderer/render_view_observer.h

Index: content/renderer/render_view_observer.h
diff --git a/content/renderer/render_view_observer.h b/content/renderer/render_view_observer.h
index 3fb5c7bfd662315b004d29dd71e604df24135ca5..167059e28d2a6d5145a689136acc6409175d4c43 100644
--- a/content/renderer/render_view_observer.h
+++ b/content/renderer/render_view_observer.h
@@ -32,6 +32,10 @@ class RenderViewObserver : public IPC::Channel::Listener,
   // they want to outlive it, they can override this function.
   virtual void OnDestruct();
 
+  // Allows certain IPC messages to be sent while swapped out, in case they
+  // are needed to keep the browser and renderer in a consistent state.
+  virtual bool CanSendWhileSwappedOut(IPC::Message* message) { return false; }
+
   // These match the WebKit API notifications
   virtual void DidStartLoading() {}
   virtual void DidStopLoading() {}