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

content/public/common/content_features.cc

Index: content/public/common/content_features.cc
diff --git a/content/public/common/content_features.cc b/content/public/common/content_features.cc
index 158f20dd6df1e6ed709744b1b9b16cb9b6aa74e2..063b2b5b8db0543ae11264dfd817055b79789a30 100644
--- a/content/public/common/content_features.cc
+++ b/content/public/common/content_features.cc
@@ -167,6 +167,9 @@ const base::Feature kPassiveDocumentEventListeners{
 const base::Feature kPassiveEventListenersDueToFling{
     "PassiveEventListenersDueToFling", base::FEATURE_ENABLED_BY_DEFAULT};
 
+const base::Feature kPredictorPreconnect{"PredictorPreconnect",
+                                         base::FEATURE_ENABLED_BY_DEFAULT};
+
 // Pointer events support.
 const base::Feature kPointerEvents{"PointerEvent",
                                    base::FEATURE_ENABLED_BY_DEFAULT};