[omnibox] Add about:flag for OmniboxUICuesForSearchHistoryMatches

Bug: 929477
Change-Id: I35ca181a114c5051dedad1843adf6bd15f4413bc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1579251
Reviewed-by: Justin Donnelly <[email protected]>
Commit-Queue: Tommy Li <[email protected]>
Cr-Commit-Position: refs/heads/master@{#653392}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 4b1cadaf..2cc335d 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -1409,6 +1409,13 @@
 const char kOmniboxUIBoldUserTextOnSearchSuggestionsDescription[] =
     "Bolds the user text instead of autocomplete text for search suggestions.";
 
+const char kOmniboxUICuesForSearchHistoryMatchesName[] =
+    "Omnibox UI Cues to Differentiate Search History Matches";
+const char kOmniboxUICuesForSearchHistoryMatchesDescription[] =
+    "Shows UI cues in the omnibox to differentiate Search History matches from "
+    "other search suggestions provided by the default search provider. This "
+    "feature is a narrow subset of Omnibox Suggestion Transparency Options.";
+
 const char kOmniboxUIHideSteadyStateUrlSchemeName[] =
     "Omnibox UI Hide Steady-State URL Scheme";
 const char kOmniboxUIHideSteadyStateUrlSchemeDescription[] =