Add about flag for Previews Omnibox UI

Bug: 871839
Change-Id: I0952b01ac1877b129b9e0e682d76a27adfb0e1bf
Reviewed-on: https://chromium-review.googlesource.com/1228490
Commit-Queue: Robert Ogden <[email protected]>
Reviewed-by: Ryan Sturm <[email protected]>
Cr-Commit-Position: refs/heads/master@{#591830}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index b2ec850..5bfc0c5 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -369,6 +369,9 @@
 extern const char kEnableHeavyPageCappingName[];
 extern const char kEnableHeavyPageCappingDescription[];
 
+extern const char kEnablePreviewsAndroidOmniboxUIName[];
+extern const char kEnablePreviewsAndroidOmniboxUIDescription[];
+
 extern const char kEnableHttpFormWarningName[];
 extern const char kEnableHttpFormWarningDescription[];