URLFetcher won't call delegate until file is closed.

net/url_request/url_fetcher_response_writer.h

 // Copyright (c) 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 NET_URL_REQUEST_URL_FETCHER_RESPONSE_WRITER_H_
 #define NET_URL_REQUEST_URL_FETCHER_RESPONSE_WRITER_H_
 
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
@@ skipping 94 matching lines @@
  private:
   // Callback which gets the result of a temporary file creation.
   void DidCreateTempFile(const CompletionCallback& callback,
                          base::FilePath* temp_file_path,
                          bool success);
 
   // Callback which gets the result of FileStream::Open.
   void DidOpenFile(const CompletionCallback& callback,
                    int result);
 
+  // Callback which gets the result of closing a file.
+  void CloseComplete(const CompletionCallback& callback, int result);
+
   // The last error encountered on a file operation.  OK if no error occurred.
   int error_code_;
 
   // Callbacks are created for use with base::FileUtilProxy.
   base::WeakPtrFactory<URLFetcherFileWriter> weak_factory_;
 
   // Task runner on which file operations should happen.
   scoped_refptr<base::TaskRunner> file_task_runner_;
 
   // Destination file path.
   // Initialize() creates a temporary file if this variable is empty.
   base::FilePath file_path_;
 
   // True when this instance is responsible to delete the file at |file_path_|.
   bool owns_file_;
 
   scoped_ptr<FileStream> file_stream_;
 
   // We always append to the file.  Track the total number of bytes
   // written, so that writes know the offset to give.
   int64 total_bytes_written_;
 
   DISALLOW_COPY_AND_ASSIGN(URLFetcherFileWriter);
 };
 
 }  // namespace net
 
 #endif  // NET_URL_REQUEST_URL_FETCHER_RESPONSE_WRITER_H_