Enable spare RenderProcessHost to be preinitialized.

chrome/browser/flag_descriptions.cc

Index: chrome/browser/flag_descriptions.cc
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 3d506ebb52eb54cee26a6edb4340bdffc72fdbdc..6e4308bfc39a18a5721aec96021d11565c35dd42 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -3046,6 +3046,12 @@ const char kOmniboxUIElideSuggestionUrlAfterHostDescription[] =
     "Elides the path, query, and ref of suggested URLs in the Omnibox "
     "dropdown.";
 
+const char kOmniboxSpareRendererName[] =
+    "Start spare renderer on omnibox focus";
+const char kOmniboxSpareRendererDescription[] =
+    "When the omnibox is focused, start an empty spare renderer. This can "
+    "speed up the load of the navigation from the omnibox.";
+
 const char kOmniboxUIHideSuggestionUrlSchemeName[] =
     "Omnibox UI Hide Suggestion URL Scheme";
 const char kOmniboxUIHideSuggestionUrlSchemeDescription[] =