Remove the iOS QR Code scanner experiment code.

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 203 matching lines @@
     return false;
   }
 
   // Check if the finch experiment is turned on
   std::string group_name =
       base::FieldTrialList::FindFullName("PhysicalWebEnabled");
   return base::StartsWith(group_name, "Enabled",
                           base::CompareCase::INSENSITIVE_ASCII);
 }
 
-bool IsQRCodeReaderEnabled() {
-  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
-  return !command_line->HasSwitch(switches::kDisableQRScanner);
-}
-
 bool IsReaderModeEnabled() {
   return base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnableReaderModeToolbarIcon);
 }
 
 bool IsReadingListEnabled() {
   return reading_list::switches::IsReadingListEnabled();
 }
 
 bool IsSafariVCSignInEnabled() {
@@ skipping 53 matching lines @@
     return true;
 
   if (command_line->HasSwitch(switches::kDisableSuggestionsUI))
     return false;
 
   // By default, disable it.
   return false;
 }
 
 }  // namespace experimental_flags