Support creating temporary files for sync file operations.

base/file_util_proxy.h

 // Copyright (c) 2011 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 BASE_FILE_UTIL_PROXY_H_
 #define BASE_FILE_UTIL_PROXY_H_
 
 #include <vector>
 
 #include "base/base_api.h"
@@ skipping 46 matching lines @@
   // for the callback.
   // If PLATFORM_FILE_CREATE is set in |file_flags| it always tries to create
   // a new file at the given |file_path| and calls back with
   // PLATFORM_FILE_ERROR_FILE_EXISTS if the |file_path| already exists.
   static bool CreateOrOpen(scoped_refptr<MessageLoopProxy> message_loop_proxy,
                            const FilePath& file_path,
                            int file_flags,
                            CreateOrOpenCallback* callback);
 
   // Creates a temporary file for writing.  The path and an open file handle
-  // are returned.  It is invalid to pass NULL for the callback.
+  // are returned.  It is invalid to pass NULL for the callback.  The additional
+  // file flags will be added on top of the default file flags which are:
+  //   base::PLATFORM_FILE_CREATE_ALWAYS
+  //   base::PLATFORM_FILE_WRITE
+  //   base::PLATFORM_FILE_TEMPORARY.
+  // Set |additional_file_flags| to 0 for synchronous writes and set to
+  // base::PLATFORM_FILE_ASYNC to support asynchronous file operations.
   static bool CreateTemporary(
       scoped_refptr<MessageLoopProxy> message_loop_proxy,
+      int additional_file_flags,
       CreateTemporaryCallback* callback);
 
   // Close the given file handle.
   static bool Close(scoped_refptr<MessageLoopProxy> message_loop_proxy,
                     PlatformFile,
                     StatusCallback* callback);
 
   // Ensures that the given |file_path| exist.  This creates a empty new file
   // at |file_path| if the |file_path| does not exist.
   // If a new file han not existed and is created at the |file_path|,
@@ skipping 127 matching lines @@
       PlatformFile file,
       StatusCallback* callback);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(FileUtilProxy);
 };
 
 }  // namespace base
 
 #endif  // BASE_FILE_UTIL_PROXY_H_