Remove the iOS QR Code scanner experiment code.

ios/chrome/browser/experimental_flags.h

 // Copyright 2014 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.
 
 #ifndef IOS_CHROME_BROWSER_EXPERIMENTAL_FLAGS_H_
 #define IOS_CHROME_BROWSER_EXPERIMENTAL_FLAGS_H_
 
 #include <string>
 
 // This file can be empty. Its purpose is to contain the relatively short lived
@@ skipping 64 matching lines @@
 
 // Whether the Payment Request API is enabled or not.
 bool IsPaymentRequestEnabled();
 
 // Whether the back-forward navigation uses pending index.
 bool IsPendingIndexNavigationEnabled();
 
 // Whether the Physical Web feature is enabled.
 bool IsPhysicalWebEnabled();
 
-// Whether the QR Code Reader is enabled.
-bool IsQRCodeReaderEnabled();
-
 // Whether reader mode is enabled.
 bool IsReaderModeEnabled();
 
 // Whether the reading list is enabled.
 bool IsReadingListEnabled();
 
 // Whether the Sign In Flow via SFSafariViewController is enabled.
 bool IsSafariVCSignInEnabled();
 
 // Whether launching actions from Spotlight is enabled.
@@ skipping 14 matching lines @@
 // Whether password generation fields are determined using local heuristics
 // only.
 bool UseOnlyLocalHeuristicsForPasswordGeneration();
 
 // Whether the Suggestions UI is enabled.
 bool IsSuggestionsUIEnabled();
 
 }  // namespace experimental_flags
 
 #endif  // IOS_CHROME_BROWSER_EXPERIMENTAL_FLAGS_H_