[RSearches] Add a new flag for Related Searches.

Adds a new chrome://flags entry for Related Searches.  This will
initially be a demo based on Contextual Search, and available to
Googlers only until it has evolved (exploration-only now).

BUG=1062737

Change-Id: I262971e7fddd188b0af3d7146076454b3616ac76
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2108901
Reviewed-by: Theresa  <[email protected]>
Commit-Queue: Donn Denman <[email protected]>
Cr-Commit-Position: refs/heads/master@{#751559}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index df47095..88287b40 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -1464,6 +1464,9 @@
 extern const char kRecoverFromNeverSaveAndroidName[];
 extern const char kRecoverFromNeverSaveAndroidDescription[];
 
+extern const char kRelatedSearchesName[];
+extern const char kRelatedSearchesDescription[];
+
 extern const char kSafeBrowsingUseLocalBlacklistsV2Name[];
 extern const char kSafeBrowsingUseLocalBlacklistsV2Description[];