Clean up CF To NS Casts and make them slightly safer

chrome/browser/importer/safari_importer.mm

 // Copyright (c) 2010 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 <Cocoa/Cocoa.h>
 
 #include "chrome/browser/importer/safari_importer.h"
 
 #include <map>
 #include <vector>
 
 #include "base/file_util.h"
+#include "base/mac/mac_util.h"
 #include "base/message_loop.h"
 #include "base/scoped_nsobject.h"
 #include "base/string16.h"
 #include "base/sys_string_conversions.h"
 #include "base/time.h"
 #include "base/values.h"
 #include "chrome/browser/history/history_types.h"
 #include "chrome/browser/importer/importer_bridge.h"
 #include "chrome/browser/importer/importer_data_types.h"
 #include "chrome/common/sqlite_utils.h"
@@ skipping 296 matching lines @@
   if (!rows.empty() && !cancelled()) {
     bridge_->SetHistoryItems(rows, history::SOURCE_SAFARI_IMPORTED);
   }
 }
 
 double SafariImporter::HistoryTimeToEpochTime(NSString* history_time) {
   DCHECK(history_time);
   // Add Difference between Unix epoch and CFAbsoluteTime epoch in seconds.
   // Unix epoch is 1970-01-01 00:00:00.0 UTC,
   // CF epoch is 2001-01-01 00:00:00.0 UTC.
-  return CFStringGetDoubleValue(reinterpret_cast<CFStringRef>(history_time)) +
+  return CFStringGetDoubleValue(base::mac::NSToCFCast(history_time)) +
       kCFAbsoluteTimeIntervalSince1970;
 }
 
 void SafariImporter::ParseHistoryItems(
     std::vector<history::URLRow>* history_items) {
   DCHECK(history_items);
 
   // Construct ~/Library/Safari/History.plist path
   NSString* library_dir = [NSString
       stringWithUTF8String:library_dir_.value().c_str()];
@@ skipping 47 matching lines @@
     if (!last_visit_str)
       continue;
 
     // Convert Safari's last visit time to Unix Epoch time.
     double seconds_since_unix_epoch = HistoryTimeToEpochTime(last_visit_str);
     row.set_last_visit(base::Time::FromDoubleT(seconds_since_unix_epoch));
 
     history_items->push_back(row);
   }
 }