[omnibox] Add about:flags entry for OmniboxSuggestionButtonRow feature

This CL creates and registers metadata for a new flag called
omnibox-suggestion-button-row.

Bug: 1046523
Change-Id: I96068d55562147a11f1fcf1524d4bb373a204875
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2026712
Commit-Queue: Orin Jaworski <[email protected]>
Reviewed-by: Tommy Li <[email protected]>
Cr-Commit-Position: refs/heads/master@{#736517}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 7711705..1d93cca 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -1613,6 +1613,9 @@
 extern const char kOmniboxPedalSuggestionsName[];
 extern const char kOmniboxPedalSuggestionsDescription[];
 
+extern const char kOmniboxSuggestionButtonRowName[];
+extern const char kOmniboxSuggestionButtonRowDescription[];
+
 extern const char kOmniboxReverseAnswersName[];
 extern const char kOmniboxReverseAnswersDescription[];