[Not Ready To Comimt] Add chrome://flags/#enable-off-main-thread-fetch

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 3e5e15d6d9fd7cd659e1feb2f354b90148e12538..c51e96ac13cd6f4c95be247dd0239d1f01bb1cc6 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2539,6 +2539,10 @@ const FeatureEntry kFeatureEntries[] = {
          kSpeculativeResourcePrefetchingFeatureVariations,
          "SpeculativeResourcePrefetchingValidation")},
 
+    {"enable-off-main-thread-fetch", flag_descriptions::kOffMainThreadFetchName,
+     flag_descriptions::kOffMainThreadFetchDescription, kOsAll,
+     FEATURE_VALUE_TYPE(features::kOffMainThreadFetch)},
+
 #if defined(OS_MACOSX)
     {"tab-strip-keyboard-focus", flag_descriptions::kTabStripKeyboardFocusName,
      flag_descriptions::kTabStripKeyboardFocusDescription, kOsMac,