Introduce OffMainThreadFetch feature

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 c1ccf0d87d5ceeb569a69fe126d8edfbb38cb6d1..6dacebc89675d492084eacb39c839cf193c72939 100644
--- a/content/public/common/content_features.cc
+++ b/content/public/common/content_features.cc
@@ -136,6 +136,10 @@ const base::Feature kNotificationContentImage{"NotificationContentImage",
 const base::Feature kMainThreadBusyScrollIntervention{
     "MainThreadBusyScrollIntervention", base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Experimental resource fetch optimizations for workers. See crbug.com/443374
+const base::Feature kOffMainThreadFetch{"OffMainThreadFetch",
+                                        base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Origin Trials for controlling access to feature/API experiments.
 const base::Feature kOriginTrials{"OriginTrials",
                                   base::FEATURE_ENABLED_BY_DEFAULT};