Create a NavigationEntry for the initial blank page.

content/public/browser/navigation_type.h

Index: content/public/browser/navigation_type.h
diff --git a/content/public/browser/navigation_type.h b/content/public/browser/navigation_type.h
index 242101b1fa1b50c957846f60eae73d7cb6af556d..4270034dd1909af1f2fea05b45bd33bf638b65e3 100644
--- a/content/public/browser/navigation_type.h
+++ b/content/public/browser/navigation_type.h
@@ -45,11 +45,6 @@ enum NavigationType {
   // These two cases are actually pretty different, they just happen to
   // require almost the same code to handle.
   NAVIGATION_TYPE_AUTO_SUBFRAME,
-
-  // Nothing happened. This happens when we get information about a page we
-  // don't know anything about. It can also happen when an iframe in a popup
-  // navigated to about:blank is navigated. Nothing needs to be done.
-  NAVIGATION_TYPE_NAV_IGNORE,
 };
 
 }  // namespace content