[filebrowser] Show progress indication, while files from GData are being downloaded.

chrome/browser/chromeos/extensions/file_browser_private_api.cc

 // Copyright (c) 2012 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/extensions/file_browser_private_api.h"
 
 #include <utility>
 
 #include "base/base64.h"
 #include "base/bind.h"
@@ skipping 1280 matching lines @@
   SET_STRING(IDS_FILE_BROWSER, DOWNLOADS_DIRECTORY_WARNING);
 
   SET_STRING(IDS_FILE_BROWSER, ERROR_CREATING_FOLDER);
   SET_STRING(IDS_FILE_BROWSER, ERROR_INVALID_CHARACTER);
   SET_STRING(IDS_FILE_BROWSER, ERROR_RESERVED_NAME);
   SET_STRING(IDS_FILE_BROWSER, ERROR_HIDDEN_NAME);
   SET_STRING(IDS_FILE_BROWSER, ERROR_WHITESPACE_NAME);
   SET_STRING(IDS_FILE_BROWSER, ERROR_NEW_FOLDER_EMPTY_NAME);
   SET_STRING(IDS_FILE_BROWSER, NEW_FOLDER_BUTTON_LABEL);
   SET_STRING(IDS_FILE_BROWSER, FILENAME_LABEL);
+  SET_STRING(IDS_FILE_BROWSER, PREPARING_LABEL);
 
   SET_STRING(IDS_FILE_BROWSER, DIMENSIONS_LABEL);
   SET_STRING(IDS_FILE_BROWSER, DIMENSIONS_FORMAT);
 
   SET_STRING(IDS_FILE_BROWSER, IMAGE_DIMENSIONS);
   SET_STRING(IDS_FILE_BROWSER, VOLUME_LABEL);
   SET_STRING(IDS_FILE_BROWSER, READ_ONLY);
 
   SET_STRING(IDS_FILE_BROWSER, ARCHIVE_MOUNT_FAILED);
   SET_STRING(IDS_FILE_BROWSER, UNMOUNT_FAILED);
@@ skipping 599 matching lines @@
       local_source_file,
       remote_destination_file,
       base::Bind(&TransferFileFunction::OnTransferCompleted,
                  this));
 }
 
 void TransferFileFunction::OnTransferCompleted(
     base::PlatformFileError error) {
   SendResponse(error == base::PLATFORM_FILE_OK);
 }