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

ios/chrome/browser/ui/util/CRUILabel+AttributeUtils.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.
 
 #include "ios/chrome/browser/ui/util/CRUILabel+AttributeUtils.h"
 
 #import <objc/runtime.h>
 
-#import "base/ios/weak_nsobject.h"
-#include "base/mac/scoped_nsobject.h"
+#include "base/logging.h"
 #import "ios/chrome/browser/ui/util/label_observer.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 // They key under which to associate the line height with the label.
 const void* const kLineHeightKey = &kLineHeightKey;
 // Creates an NSNumber from |line_height| and associates it with |label|.
 void SetAssociatedLineHeight(CGFloat line_height, UILabel* label) {
   objc_setAssociatedObject(label, kLineHeightKey, @(line_height),
                            OBJC_ASSOCIATION_RETAIN_NONATOMIC);
 }
 // Returns the line height associated with |label|.
 CGFloat GetAssociatedLineHeight(UILabel* label) {
@@ skipping 27 matching lines @@
   }
 
   // Store the new line height as an associated object.
   SetAssociatedLineHeight(lineHeight, self);
 
   // If there's no text yet, there's nothing that can be done.  The
   // LabelObserverAction will call this selector again upon changes to the text.
   if (!self.text.length || !self.attributedText.string.length)
     return;
 
-  base::scoped_nsobject<NSMutableAttributedString> newString(
-      [self.attributedText mutableCopy]);
+  NSMutableAttributedString* newString = [self.attributedText mutableCopy];
   DCHECK([newString length]);
   NSParagraphStyle* style = [newString attribute:NSParagraphStyleAttributeName
                                          atIndex:0
                                   effectiveRange:nullptr];
   if (!style)
     style = [NSParagraphStyle defaultParagraphStyle];
-  base::scoped_nsobject<NSMutableParagraphStyle> newStyle([style mutableCopy]);
+  NSMutableParagraphStyle* newStyle = [style mutableCopy];
   [newStyle setMinimumLineHeight:lineHeight];
   [newStyle setMaximumLineHeight:lineHeight];
   [newString addAttribute:NSParagraphStyleAttributeName
                     value:newStyle
                     range:NSMakeRange(0, [newString length])];
   self.attributedText = newString;
 }
 
 @end