Clean up CF To NS Casts and make them slightly safer

chrome/browser/cocoa/keystone_glue.mm

 // Copyright (c) 2009 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 "chrome/browser/cocoa/keystone_glue.h"
 
 #include <sys/param.h>
 #include <sys/mount.h>
 
 #include <vector>
@@ skipping 739 matching lines @@
     // asynchronous operation is pending, or even after promotion has already
     // occurred.  Just quietly return without doing anything.
     return;
   }
 
   NSString* prompt = l10n_util::GetNSStringFWithFixup(
       IDS_PROMOTE_AUTHENTICATION_PROMPT,
       l10n_util::GetStringUTF16(IDS_PRODUCT_NAME));
   scoped_AuthorizationRef authorization(
       authorization_util::AuthorizationCreateToRunAsRoot(
-          reinterpret_cast<CFStringRef>(prompt)));
+          base::mac::NSToCFCast(prompt)));
   if (!authorization.get()) {
     return;
   }
 
   [self promoteTicketWithAuthorization:authorization.release() synchronous:NO];
 }
 
 - (void)promoteTicketWithAuthorization:(AuthorizationRef)authorization_arg
                            synchronous:(BOOL)synchronous {
   scoped_AuthorizationRef authorization(authorization_arg);
@@ skipping 177 matching lines @@
   return [KeystoneGlue defaultKeystoneGlue] != nil;
 }
 
 string16 CurrentlyInstalledVersion() {
   KeystoneGlue* keystoneGlue = [KeystoneGlue defaultKeystoneGlue];
   NSString* version = [keystoneGlue currentlyInstalledVersion];
   return base::SysNSStringToUTF16(version);
 }
 
 }  // namespace keystone_glue