Use sequenced blocking pool task to create PNaCl's nexe temp file

chrome/browser/nacl_host/pnacl_host.h

 // Copyright 2013 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.
 
 #ifndef CHROME_BROWSER_NACL_HOST_PNACL_HOST_H_
 #define CHROME_BROWSER_NACL_HOST_PNACL_HOST_H_
 
 #include <map>
 
 #include "base/callback_forward.h"
@@ skipping 111 matching lines @@
     std::string cache_key;
     nacl::PnaclCacheInfo cache_info;
   };
 
   typedef std::pair<int, int> TranslationID;
   typedef std::map<TranslationID, PendingTranslation> PendingTranslationMap;
 
   void InitForTest(base::FilePath temp_dir);
   void OnCacheInitialized(int net_error);
 
-  static base::PlatformFile DoCreateTemporaryFile(base::FilePath temp_dir_);
+  static void DoCreateTemporaryFile(base::FilePath temp_dir_,
+                                    TempFileCallback cb);
 
   // GetNexeFd common steps
   void SendCacheQueryAndTempFileRequest(const std::string& key,
                                         const TranslationID& id);
   void OnCacheQueryReturn(const TranslationID& id,
                           int net_error,
                           scoped_refptr<net::DrainableIOBuffer> buffer);
   void OnTempFileReturn(const TranslationID& id, base::PlatformFile fd);
   void CheckCacheQueryReady(const PendingTranslationMap::iterator& entry);
 
@@ skipping 16 matching lines @@
   CacheState cache_state_;
   base::FilePath temp_dir_;
   scoped_ptr<pnacl::PnaclTranslationCache> disk_cache_;
   PendingTranslationMap pending_translations_;
   base::ThreadChecker thread_checker_;
   base::WeakPtrFactory<PnaclHost> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(PnaclHost);
 };
 
 #endif  // CHROME_BROWSER_NACL_HOST_PNACL_HOST_H_