Removed IsNativeAppLauncherEnabled() experiment

ios/chrome/browser/experimental_flags.mm

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file can be empty. Its purpose is to contain the relatively short lived
 // definitions required for experimental flags.
 
 #include "ios/chrome/browser/experimental_flags.h"
 
 #include <dispatch/dispatch.h>
@@ skipping 244 matching lines @@
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(switches::kEnableSigninPromo))
     return true;
   if (command_line->HasSwitch(switches::kDisableSigninPromo))
     return false;
   std::string group_name = base::FieldTrialList::FindFullName("IOSSigninPromo");
   return base::StartsWith(group_name, "Enabled",
                           base::CompareCase::INSENSITIVE_ASCII);
 }
 
-bool IsNativeAppLauncherEnabled() {
-  return [[NSUserDefaults standardUserDefaults]
-      boolForKey:@"NativeAppLauncherEnabled"];
-}
-
 }  // namespace experimental_flags