[ObjC ARC] Converts ios/chrome/browser/ui/qr_scanner:eg_tests to ARC.

ios/chrome/browser/ui/qr_scanner/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.
 
 bundle_data("assets") {
   sources = [
     "resources/QRScanner.xcassets/Contents.json",
     "resources/QRScanner.xcassets/qr_scanner_torch_off.imageset/Contents.json",
     "resources/QRScanner.xcassets/qr_scanner_torch_off.imageset/torch_off.png",
     "resources/QRScanner.xcassets/qr_scanner_torch_off.imageset/torch_off@2x.png",
@@ skipping 34 matching lines @@
     "//ios/third_party/material_components_ios",
     "//ui/base",
   ]
   libs = [
     "AVFoundation.framework",
     "UIKit.framework",
   ]
 }
 
 source_set("eg_tests") {
+  configs += [ "//build/config/compiler:enable_arc" ]
   testonly = true
   sources = [
     "qr_scanner_view_controller_egtest.mm",
   ]
   deps = [
     ":qr_scanner",
     "//base",
     "//base/test:test_support",
     "//components/strings",
     "//components/version_info",
@@ skipping 12 matching lines @@
     "//ios/third_party/earl_grey",
     "//ios/web:test_support",
     "//third_party/ocmock",
     "//ui/base",
   ]
   libs = [
     "AVFoundation.framework",
     "UIKit.framework",
   ]
 }