Add a parameter to FileStreamWriter::CreateForLocalFile to allow creating new

chrome/browser/chromeos/drive/fileapi/webkit_file_stream_writer_impl.cc

 // Copyright 2014 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.
 
 #include "chrome/browser/chromeos/drive/fileapi/webkit_file_stream_writer_impl.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "chrome/browser/chromeos/drive/file_system_util.h"
 #include "chrome/browser/chromeos/drive/fileapi/fileapi_worker.h"
@@ skipping 151 matching lines @@
     DCHECK(close_callback_on_ui_thread.is_null());
     callback.Run(
         net::FileErrorToNetError(open_result));
     return;
   }
 
   // Keep |close_callback| to close the file when the stream is destructed.
   DCHECK(!close_callback_on_ui_thread.is_null());
   close_callback_on_ui_thread_ = close_callback_on_ui_thread;
   local_file_writer_.reset(fileapi::FileStreamWriter::CreateForLocalFile(
-      file_task_runner_.get(), local_path, offset_));
+      file_task_runner_.get(), local_path, offset_,
+      fileapi::FileStreamWriter::OPEN_EXISTING_FILE));
   int result = local_file_writer_->Write(buf, buf_len, callback);
   if (result != net::ERR_IO_PENDING)
     callback.Run(result);
 }
 
 }  // namespace internal
 }  // namespace drive