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.  If async
+  // is true the file temporary file will be opened to support asynchronuous
+  // file operations.  Set async to false if you want to use
+  // FileUtilProxy::Write() on the temporary file.
   static bool CreateTemporary(
       scoped_refptr<MessageLoopProxy> message_loop_proxy,
+      bool aync,

[darin (slow to review), 2011/06/03 17:51:45]

please avoid adding bool parameters like this.  it makes the callsite very
unreadable.  you just see true/false, with no idea what it means.  it is better
to define an enum.

another option is to create a separate function name, which describes the
variant you want.

however, i also want to ask:  why are you using FileUtilProxy::Write and not
net::FileStream to write to a file?

       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_