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

ios/chrome/browser/ui/toolbar/new_tab_button.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.
 
 #import "ios/chrome/browser/ui/toolbar/new_tab_button.h"
 
 #include "base/logging.h"
 #import "ios/chrome/browser/ui/commands/UIKit+ChromeExecuteCommand.h"
 #include "ios/chrome/browser/ui/commands/ios_command_ids.h"
 #import "ios/chrome/browser/ui/image_util.h"
 #import "ios/chrome/browser/ui/rtl_geometry.h"
 #import "ios/chrome/browser/ui/uikit_ui_util.h"
 #import "ios/chrome/common/material_timing.h"
 #include "ios/chrome/grit/ios_strings.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 // Amount by which to inset the button's content.
 const CGFloat kContentInset = 6.0;
 
 // Duration of transition animation.
 const NSTimeInterval kNewTabButtonTransitionDuration =
     ios::material::kDuration1;
 }
 
 @implementation NewTabButton
@@ skipping 48 matching lines @@
                     animations:^{
                       self.incognito = incognito;
                     }
                     completion:nil];
   } else {
     self.incognito = incognito;
   }
 }
 
 @end