Additional fixes for prerender/instant + browsing history.

content/browser/tab_contents/navigation_controller.cc

Index: content/browser/tab_contents/navigation_controller.cc
diff --git a/content/browser/tab_contents/navigation_controller.cc b/content/browser/tab_contents/navigation_controller.cc
index 0144fef9b691ea047279e75249cd6688102e25f0..2722535c130a1c912d7b547d30c46c00e4719626 100644
--- a/content/browser/tab_contents/navigation_controller.cc
+++ b/content/browser/tab_contents/navigation_controller.cc
@@ -933,7 +933,15 @@ void NavigationController::CopyStateFromAndPrune(NavigationController* source,
   }
 
   // Update the history in the RenderView.
-  tab_contents_->SetHistoryLengthAndClear(max_source_index);
+  // Note, I don't know if this makes sense if the active entry is transient.
+  NavigationEntry* active_entry = GetActiveEntry();
+  if (!active_entry) {
+    LOG(ERROR) << "!active_entry";
+    return;
+  }
+  tab_contents_->SetHistoryLengthAndClear(active_entry->site_instance(),
+                                          max_source_index,
+                                          active_entry->page_id());
 }
 
 void NavigationController::PruneAllButActive() {