Add new-net-error-page-ui feature flag

Bug: 852872
Change-Id: Id8211211920db4ee977ea0dfd665b0c571ccd224
Reviewed-on: https://chromium-review.googlesource.com/1147090
Commit-Queue: Dan H <[email protected]>
Reviewed-by: Shakti Sahu <[email protected]>
Reviewed-by: Carlos Knippschild <[email protected]>
Cr-Commit-Position: refs/heads/master@{#579097}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index a7c1e67..bd91958 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -1487,6 +1487,9 @@
 extern const char kNewContactsPickerName[];
 extern const char kNewContactsPickerDescription[];
 
+extern const char kNewNetErrorPageUIName[];
+extern const char kNewNetErrorPageUIDescription[];
+
 extern const char kNewPhotoPickerName[];
 extern const char kNewPhotoPickerDescription[];