Limit the number of history urls indexed for omnibox suggestions.

components/omnibox/browser/omnibox_switches.cc

Index: components/omnibox/browser/omnibox_switches.cc
diff --git a/components/omnibox/browser/omnibox_switches.cc b/components/omnibox/browser/omnibox_switches.cc
index a17a27e4e745891670d18cbb532138bfbd1f984e..6a89d19ec5621ee105e6dd2b08ce5627de63fb62 100644
--- a/components/omnibox/browser/omnibox_switches.cc
+++ b/components/omnibox/browser/omnibox_switches.cc
@@ -11,4 +11,9 @@ namespace switches {
 const char kEmphasizeTitlesInOmniboxDropdown[] =
     "emphasize-titles-in-omnibox-dropdown";
 
+// Picks the top |N| from history URLs for indexing in omnibox suggestions.
+// Takes a single argument |N|.
+extern const char kLimitHistoryUrlIndexingForOmnibox[] =
+    "limit-history-url-indexing-for-omnibox";
+
 }  // namespace switches