Use singular when only one item is selected.

chrome/browser/chromeos/extensions/file_manager/private_api_strings.cc

 // Copyright 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.
 
 #include "chrome/browser/chromeos/extensions/file_manager/private_api_strings.h"
 
 #include "base/strings/stringprintf.h"
 #include "base/sys_info.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chromeos/file_manager/open_with_browser.h"
@@ skipping 492 matching lines @@
   SET_STRING("NO_TASK_FOR_CRX", IDS_FILE_BROWSER_NO_TASK_FOR_CRX);
   SET_STRING("NO_TASK_FOR_CRX_TITLE", IDS_FILE_BROWSER_NO_TASK_FOR_CRX_TITLE);
   SET_STRING("NO_TASK_FOR_DMG", IDS_FILE_BROWSER_NO_TASK_FOR_DMG);
   SET_STRING("NO_TASK_FOR_EXECUTABLE", IDS_FILE_BROWSER_NO_TASK_FOR_EXECUTABLE);
   SET_STRING("NO_TASK_FOR_FILE", IDS_FILE_BROWSER_NO_TASK_FOR_FILE);
   SET_STRING("OFFLINE_COLUMN_LABEL", IDS_FILE_BROWSER_OFFLINE_COLUMN_LABEL);
   SET_STRING("OFFLINE_HEADER", IDS_FILE_BROWSER_OFFLINE_HEADER);
   SET_STRING("OFFLINE_MESSAGE", IDS_FILE_BROWSER_OFFLINE_MESSAGE);
   SET_STRING("OFFLINE_MESSAGE_PLURAL", IDS_FILE_BROWSER_OFFLINE_MESSAGE_PLURAL);
   SET_STRING("OK_LABEL", IDS_FILE_BROWSER_OK_LABEL);
+  SET_STRING("ONE_DIRECTORY_SELECTED", IDS_FILE_BROWSER_ONE_DIRECTORY_SELECTED);
+  SET_STRING("ONE_FILE_SELECTED", IDS_FILE_BROWSER_ONE_FILE_SELECTED);
   SET_STRING("OPEN_IN_OTHER_DESKTOP_MESSAGE",
              IDS_FILE_BROWSER_OPEN_IN_OTHER_DESKTOP_MESSAGE);
   SET_STRING("OPEN_IN_OTHER_DESKTOP_MESSAGE_PLURAL",
              IDS_FILE_BROWSER_OPEN_IN_OTHER_DESKTOP_MESSAGE_PLURAL);
   SET_STRING("OPEN_LABEL", IDS_FILE_BROWSER_OPEN_LABEL);
   SET_STRING("OPEN_WITH_BUTTON_LABEL", IDS_FILE_BROWSER_OPEN_WITH_BUTTON_LABEL);
   SET_STRING("PASTE_BUTTON_LABEL", IDS_FILE_BROWSER_PASTE_BUTTON_LABEL);
   SET_STRING("PASTE_INTO_FOLDER_BUTTON_LABEL",
              IDS_FILE_BROWSER_PASTE_INTO_FOLDER_BUTTON_LABEL);
   SET_STRING("PREPARING_LABEL", IDS_FILE_BROWSER_PREPARING_LABEL);
@@ skipping 116 matching lines @@
       base::StringPrintf(kHelpURLFormat, kNoActionForFileHelpNumber));
   dict->SetString("UI_LOCALE", extension_l10n_util::CurrentLocaleOrDefault());
 
   const std::string& app_locale = g_browser_process->GetApplicationLocale();
   webui::SetLoadTimeDataDefaults(app_locale, dict);
 
   return true;
 }
 
 }  // namespace extensions