[Not for review] Add TRACE_EVENTs and chrome://flags for preconnect

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 9f7f877601d169d29be6c48ac521203f303b44f9..d4b8a332f6d430ef0b74f2843ceeb515ca6db2d8 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -1048,6 +1048,10 @@ const char kPasswordImportExportDescription[] =
 const char kProtectSyncCredentialOnReauthName[] =
     "Autofill sync credential only for transactional reauth pages";
 
+const char kPredictorPreconnectName[] = "Predictor preconnect";
+
+const char kPredictorPreconnectDescription[] = "Enable predictor preconnect.";
+
 const char kProtectSyncCredentialOnReauthDescription[] =
     "How the password manager handles autofill for the sync credential only "
     "for transactional reauth pages.";