Rewrite std::string("") to std::string(), Linux edition.

base/file_util_unittest.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 "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #include <shlobj.h>
@@ skipping 1828 matching lines @@
   // create the directories
   FilePath dir1 = temp_dir_.path().Append(FILE_PATH_LITERAL("dir1"));
   EXPECT_TRUE(file_util::CreateDirectory(dir1));
   FilePath dir2 = temp_dir_.path().Append(FILE_PATH_LITERAL("dir2"));
   EXPECT_TRUE(file_util::CreateDirectory(dir2));
   FilePath dir2inner = dir2.Append(FILE_PATH_LITERAL("inner"));
   EXPECT_TRUE(file_util::CreateDirectory(dir2inner));
 
   // create the files
   FilePath dir2file = dir2.Append(FILE_PATH_LITERAL("dir2file.txt"));
-  CreateTextFile(dir2file, L"");
+  CreateTextFile(dir2file, std::wstring());
   FilePath dir2innerfile = dir2inner.Append(FILE_PATH_LITERAL("innerfile.txt"));
-  CreateTextFile(dir2innerfile, L"");
+  CreateTextFile(dir2innerfile, std::wstring());
   FilePath file1 = temp_dir_.path().Append(FILE_PATH_LITERAL("file1.txt"));
-  CreateTextFile(file1, L"");
-  FilePath file2_rel =
-      dir2.Append(FilePath::kParentDirectory)
-          .Append(FILE_PATH_LITERAL("file2.txt"));
-  CreateTextFile(file2_rel, L"");
+  CreateTextFile(file1, std::wstring());
+  FilePath file2_rel = dir2.Append(FilePath::kParentDirectory)
+      .Append(FILE_PATH_LITERAL("file2.txt"));
+  CreateTextFile(file2_rel, std::wstring());
   FilePath file2_abs = temp_dir_.path().Append(FILE_PATH_LITERAL("file2.txt"));
 
   // Only enumerate files.
   file_util::FileEnumerator f1(temp_dir_.path(), true,
                                file_util::FileEnumerator::FILES);
   FindResultCollector c1(f1);
   EXPECT_TRUE(c1.HasFile(file1));
   EXPECT_TRUE(c1.HasFile(file2_abs));
   EXPECT_TRUE(c1.HasFile(dir2file));
   EXPECT_TRUE(c1.HasFile(dir2innerfile));
@@ skipping 555 matching lines @@
       file_util::VerifyPathControlledByUser(
           base_dir_, text_file_, uid_, ok_gids_));
   EXPECT_TRUE(
       file_util::VerifyPathControlledByUser(
           sub_dir_, text_file_, uid_, ok_gids_));
 }
 
 #endif  // defined(OS_POSIX)
 
 }  // namespace