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

ios/chrome/browser/chrome_url_util.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/chrome_url_util.h"
 
 #import <UIKit/UIKit.h>
 
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
 #include "base/mac/scoped_block.h"
-#include "base/mac/scoped_nsobject.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "ios/chrome/browser/chrome_url_constants.h"
 #import "ios/net/url_scheme_util.h"
 #include "net/url_request/url_request.h"
 #include "url/gurl.h"
 #include "url/url_constants.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 bool UrlIsExternalFileReference(const GURL& url) {
   return url.SchemeIs(kChromeUIScheme) &&
          base::LowerCaseEqualsASCII(url.host(), kChromeUIExternalFileHost);
 }
 
 bool UrlHasChromeScheme(const GURL& url) {
   return url.SchemeIs(kChromeUIScheme);
 }
 
 bool UrlHasChromeScheme(NSURL* url) {
   return net::UrlSchemeIs(url, base::SysUTF8ToNSString(kChromeUIScheme));
 }
 
 bool IsHandledProtocol(const std::string& scheme) {
   DCHECK_EQ(scheme, base::ToLowerASCII(scheme));
   if (scheme == url::kAboutScheme)
     return true;
   if (scheme == url::kDataScheme)
     return true;
   if (scheme == kChromeUIScheme)
     return true;
   return net::URLRequest::IsHandledProtocol(scheme);
 }
 
 @implementation ChromeAppConstants {
-  base::scoped_nsobject<NSString> _callbackScheme;
+  NSString* _callbackScheme;
 }
 
 + (ChromeAppConstants*)sharedInstance {
   static ChromeAppConstants* g_instance = [[ChromeAppConstants alloc] init];
   return g_instance;
 }
 
 - (NSString*)getBundleURLScheme {
   if (!_callbackScheme) {
     NSSet* allowableSchemes =
         [NSSet setWithObjects:@"googlechrome", @"chromium",
                               @"ios-chrome-unittests.http", nil];
     NSDictionary* info = [[NSBundle mainBundle] infoDictionary];
     NSArray* urlTypes = [info objectForKey:@"CFBundleURLTypes"];
     for (NSDictionary* urlType in urlTypes) {
       DCHECK([urlType isKindOfClass:[NSDictionary class]]);
       NSArray* schemes =
           base::mac::ObjCCastStrict<NSArray>(urlType[@"CFBundleURLSchemes"]);
       for (NSString* scheme in schemes) {
         if ([allowableSchemes containsObject:scheme])
-          _callbackScheme.reset([scheme copy]);
+          _callbackScheme = [scheme copy];
       }
     }
   }
   DCHECK([_callbackScheme length]);
   return _callbackScheme;
 }
 
 - (void)setCallbackSchemeForTesting:(NSString*)scheme {
-  _callbackScheme.reset([scheme copy]);
+  _callbackScheme = [scheme copy];
 }
 
 @end