Support creating temporary files for sync file operations.

base/file_util_proxy.h

Index: base/file_util_proxy.h
diff --git a/base/file_util_proxy.h b/base/file_util_proxy.h
index e0b04cb220abd5259c031bef189b5d88ce49930f..8385c880e79a4f5a43dfeed9cf4672c226e1858d 100644
--- a/base/file_util_proxy.h
+++ b/base/file_util_proxy.h
@@ -64,9 +64,17 @@ class BASE_API FileUtilProxy {
                            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 for
+  // net::FileStream.

[darin (slow to review), 2011/06/11 07:00:37]

nit: it is risky to refer to another module like this.  what happens if
net::FileStream is renamed?  will people know to look here to fix the comment? 
I'd probably just drop the "for net::FileStream" part.

[noelutz, 2011/06/13 16:52:08]

Done.

   static bool CreateTemporary(
       scoped_refptr<MessageLoopProxy> message_loop_proxy,
+      int additional_file_flags,
       CreateTemporaryCallback* callback);
 
   // Close the given file handle.