Revert of Fix nullptr exception on ios_internal

ios/chrome/browser/reading_list/reading_list_model_factory.cc

Index: ios/chrome/browser/reading_list/reading_list_model_factory.cc
diff --git a/ios/chrome/browser/reading_list/reading_list_model_factory.cc b/ios/chrome/browser/reading_list/reading_list_model_factory.cc
index 759f00d759632c81912b96645db8e531ce8906ea..5be056091b0e061fc1c64f957c0e18d4c9b75b54 100644
--- a/ios/chrome/browser/reading_list/reading_list_model_factory.cc
+++ b/ios/chrome/browser/reading_list/reading_list_model_factory.cc
@@ -17,11 +17,6 @@
 #include "ios/chrome/browser/reading_list/reading_list_pref_names.h"
 
 // static
-bool ReadingListModelFactory::IsReadingListEnabled() {
-  return experimental_flags::IsReadingListEnabled();
-}
-
-// static
 ReadingListModel* ReadingListModelFactory::GetForBrowserState(
     ios::ChromeBrowserState* browser_state) {
   return static_cast<ReadingListModelImpl*>(