Remove the iOS QR Code scanner experiment code.

ios/chrome/app/resources/BUILD.gn

 # Copyright 2016 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.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/ios/rules.gni")
 import("//build/config/locales.gni")
 import("//ios/chrome/app/resources/ios_chrome_repack.gni")
 import("//ios/chrome/tools/strings/generate_localizable_strings.gni")
 import("//ios/public/provider/chrome/browser/build_config.gni")
@@ skipping 79 matching lines @@
     "{{bundle_resources_dir}}/{{source_file_part}}",
   ]
 }
 
 bundle_data("quick_action_icons") {
   sources = [
     "quick_action_new_incognito_tab@2x.png",
     "quick_action_new_incognito_tab@3x.png",
     "quick_action_new_tab@2x.png",
     "quick_action_new_tab@3x.png",
+    "quick_action_qr_scanner@2x.png",
+    "quick_action_qr_scanner@3x.png",
     "quick_action_voice_search@2x.png",
     "quick_action_voice_search@3x.png",
   ]
   outputs = [
     "{{bundle_resources_dir}}/{{source_file_part}}",
   ]
 }
 
 bundle_data("launchscreen_assets") {
   sources = [
@@ skipping 20 matching lines @@
   datapack_dir = get_label_info(ios_packed_resources_target, "target_gen_dir")
   packed_locales = ios_packed_locales_as_mac_outputs
   output_filenames = [
     "InfoPlist.strings",
     "Localizable.strings",
   ]
   deps = [
     ios_packed_resources_target,
   ]
 }