Update entry page type to include error pages when appropriate.

At present, the NavigationEntry page type always reports
PAGE_TYPE_NORMAL for all committed entries, even if an
error page is currently showing. There is a need for a
mechanism to detect when an error page is showing in order
to prevent zooming in that case, so we modify the
navigation entry to correctly report error pages.

BUG=403268

Review URL: https://codereview.chromium.org/580133002

Cr-Commit-Position: refs/heads/master@{#296614}
diff --git a/content/browser/frame_host/navigation_controller_impl.cc b/content/browser/frame_host/navigation_controller_impl.cc
index 3b53e58..4be5a3ce 100644
--- a/content/browser/frame_host/navigation_controller_impl.cc
+++ b/content/browser/frame_host/navigation_controller_impl.cc
@@ -1060,6 +1060,8 @@
     update_virtual_url = needs_update;
   }
 
+  if (params.url_is_unreachable)
+    new_entry->set_page_type(PAGE_TYPE_ERROR);
   new_entry->SetURL(params.url);
   if (update_virtual_url)
     UpdateVirtualURLToURL(new_entry, params.url);