Add DCHECK that Reload should never be called with ReloadType::NONE

content/public/browser/navigation_controller.h

Index: content/public/browser/navigation_controller.h
diff --git a/content/public/browser/navigation_controller.h b/content/public/browser/navigation_controller.h
index 7ec3ca82f17a394952d5eb8222fb78e7f09d6567..4ece52b3df2a8e9ec780379c87938f386fa81ccf 100644
--- a/content/public/browser/navigation_controller.h
+++ b/content/public/browser/navigation_controller.h
@@ -356,6 +356,7 @@ class NavigationController {
   // cases pass in true in production code, but would do false for testing, or
   // in cases where no user interface is available for prompting.  If a
   // transient entry is showing, initiates a new navigation to its URL.
+  // NOTE: |reload_type| should never be NONE.
   virtual void Reload(ReloadType reload_type, bool check_for_repost) = 0;
 
   // Removing of entries -------------------------------------------------------