Introduce Zero Prefix URL Suggestions flag.

This flag controls support for Omnibox Zero Prefix URL Suggestions on Clank.
When enabled, Omnibox will start supplying suggestions for currently visited
website.

Bug: 934922
Change-Id: Ic28e81855198c5a21e1c0e2eeee02629f422ca1f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1516713
Reviewed-by: Filip Gorski <[email protected]>
Reviewed-by: Matthew Jones <[email protected]>
Reviewed-by: Mark Pearson <[email protected]>
Commit-Queue: Ender <[email protected]>
Cr-Commit-Position: refs/heads/master@{#641327}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 6d65323..9a7c87ec 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -872,6 +872,9 @@
 extern const char kOmniboxVoiceSearchAlwaysVisibleName[];
 extern const char kOmniboxVoiceSearchAlwaysVisibleDescription[];
 
+extern const char kOmniboxZeroSuggestionsOnNTPName[];
+extern const char kOmniboxZeroSuggestionsOnNTPDescription[];
+
 extern const char kOnTheFlyMhtmlHashComputationName[];
 extern const char kOnTheFlyMhtmlHashComputationDescription[];