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

ios/chrome/browser/ui/icons/chrome_icon.mm

 // 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 "ios/chrome/browser/ui/icons/chrome_icon.h"
 
 #import <CoreGraphics/CoreGraphics.h>
 
 #include "base/logging.h"
-#import "base/mac/scoped_nsobject.h"
 #include "ios/chrome/grit/ios_strings.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 {
 
 NSString* AccessibilityLabelForIconNamed(NSString* name) {
   if ([name isEqualToString:@"ic_arrow_back"])
     return l10n_util::GetNSString(IDS_IOS_ICON_ARROW_BACK);
   if ([name isEqualToString:@"ic_close"])
     return l10n_util::GetNSString(IDS_IOS_ICON_CLOSE);
   if ([name isEqualToString:@"ic_info"])
     return l10n_util::GetNSString(IDS_IOS_ICON_INFO);
   if ([name isEqualToString:@"ic_search"])
@@ skipping 42 matching lines @@
 + (UIImage*)chevronIcon {
   return ImageFlippedForRightToLeftLayoutDirection(
       IconNamed(@"ic_chevron_right"));
 }
 
 + (UIBarButtonItem*)templateBarButtonItemWithImage:(UIImage*)image
                                             target:(id)target
                                             action:(SEL)action {
   UIImage* templateImage =
       [image imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
-  base::scoped_nsobject<UIBarButtonItem> barButtonItem([[UIBarButtonItem alloc]
-      initWithImage:templateImage
-              style:UIBarButtonItemStylePlain
-             target:target
-             action:action]);
+  UIBarButtonItem* barButtonItem =
+      [[UIBarButtonItem alloc] initWithImage:templateImage
+                                       style:UIBarButtonItemStylePlain
+                                      target:target
+                                      action:action];
   [barButtonItem setAccessibilityIdentifier:image.accessibilityIdentifier];
   [barButtonItem setAccessibilityLabel:image.accessibilityLabel];
-  return barButtonItem.autorelease();
+  return barButtonItem;
 }
 
 @end