OOPIF: Fix willSendRequest in A-B-A nested case.

content/browser/frame_host/navigation_controller_impl.cc

Index: content/browser/frame_host/navigation_controller_impl.cc
diff --git a/content/browser/frame_host/navigation_controller_impl.cc b/content/browser/frame_host/navigation_controller_impl.cc
index 321aaeac80253402894b3e0a816d83a00f87001c..cc6fb574cdd7fec6dfe0a2b4deb9d3a8e1e1d174 100644
--- a/content/browser/frame_host/navigation_controller_impl.cc
+++ b/content/browser/frame_host/navigation_controller_impl.cc
@@ -1177,10 +1177,7 @@ void NavigationControllerImpl::RendererDidNavigateToExistingPage(
   if (ui::PageTransitionIsRedirect(params.transition))
     entry->GetFavicon() = FaviconStatus();
 
-  // The site instance will normally be the same except during session restore,
-  // when no site instance will be assigned.
-  DCHECK(entry->site_instance() == NULL ||
-         entry->site_instance() == rfh->GetSiteInstance());
+  // The SiteInstance can change for cross-process location.replace navigations.
   entry->set_site_instance(
       static_cast<SiteInstanceImpl*>(rfh->GetSiteInstance()));