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

ios/chrome/browser/about_flags.mm

 // Copyright 2012 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.
 
 // Implementation of about_flags for iOS that sets flags based on experimental
 // settings.
 
 #include "ios/chrome/browser/about_flags.h"
 
 #include <stddef.h>
@@ skipping 20 matching lines @@
 #include "components/sync/driver/sync_driver_switches.h"
 #include "google_apis/gaia/gaia_switches.h"
 #include "ios/chrome/browser/chrome_switches.h"
 #include "ios/chrome/browser/google_api_keys.h"
 #include "ios/chrome/grit/ios_strings.h"
 #include "ios/web/public/user_agent.h"
 #include "ios/web/public/web_view_creation_util.h"
 
 #if !defined(OFFICIAL_BUILD)
 #include "components/variations/variations_switches.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
 #endif
 
 namespace {
 // To add a new entry, add to the end of kFeatureEntries. There are two
 // distinct types of entries:
 // . SINGLE_VALUE: entry is either on or off. Use the SINGLE_VALUE_TYPE
 //   macro for this type supplying the command line to the macro.
 // . MULTI_VALUE: a list of choices, the first of which should correspond to a
 //   deactivated state for this lab (i.e. no command line option).  To specify
 //   this type of entry use the macro MULTI_VALUE_TYPE supplying it the
@@ skipping 290 matching lines @@
 }
 
 namespace testing {
 
 const flags_ui::FeatureEntry* GetFeatureEntries(size_t* count) {
   *count = arraysize(kFeatureEntries);
   return kFeatureEntries;
 }
 
 }  // namespace testing