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

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>
 #import <Foundation/Foundation.h>
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "components/autofill/core/common/autofill_switches.h"
 #include "components/reading_list/core/reading_list_switches.h"
 #include "components/variations/variations_associated_data.h"
 #include "ios/chrome/browser/chrome_switches.h"
 #include "ios/web/public/web_view_creation_util.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 NSString* const kEnableAlertOnBackgroundUpload =
     @"EnableAlertsOnBackgroundUpload";
 NSString* const kEnableNewClearBrowsingDataUI = @"EnableNewClearBrowsingDataUI";
 NSString* const kEnableStartupCrash = @"EnableStartupCrash";
 NSString* const kEnableViewCopyPasswords = @"EnableViewCopyPasswords";
 NSString* const kExternalAppPromptDisabled = @"ExternalAppPromptDisabled";
 NSString* const kFirstRunForceEnabled = @"FirstRunForceEnabled";
 NSString* const kForceResetContextualSearch = @"ForceResetContextualSearch";
@@ skipping 261 matching lines @@
   if ([[NSUserDefaults standardUserDefaults]
           boolForKey:kHeuristicsForPasswordGeneration]) {
     return true;
   }
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   return command_line->HasSwitch(
       autofill::switches::kLocalHeuristicsOnlyForPasswordGeneration);
 }
 
 }  // namespace experimental_flags