Update from https://crrev.com/314320

base/i18n/file_util_icu.h

 // 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.
 
 #ifndef BASE_I18N_FILE_UTIL_ICU_H_
 #define BASE_I18N_FILE_UTIL_ICU_H_
 
 // File utilities that use the ICU library go in this file.
 
 #include "base/files/file_path.h"
 #include "base/i18n/base_i18n_export.h"
 #include "base/strings/string16.h"
 
 namespace base {
 namespace i18n {
 
 // Returns true if file_name does not have any illegal character. The input
 // param has the same restriction as that for ReplaceIllegalCharacters.
 BASE_I18N_EXPORT bool IsFilenameLegal(const string16& file_name);
 
-// Replaces characters in 'file_name' that are illegal for file names with
-// 'replace_char'. 'file_name' must not be a full or relative path, but just the
+// Replaces characters in |file_name| that are illegal for file names with
+// |replace_char|. |file_name| must not be a full or relative path, but just the
 // file name component (since slashes are considered illegal). Any leading or
-// trailing whitespace in 'file_name' is removed.
+// trailing whitespace or periods in |file_name| is also replaced with the
+// |replace_char|.
+//
 // Example:
-//   file_name == "bad:file*name?.txt", changed to: "bad-file-name-.txt" when
-//   'replace_char' is '-'.
+//   "bad:file*name?.txt" will be turned into "bad_file_name_.txt" when
+//   |replace_char| is '_'.
+//
+// Warning: Do not use this function as the sole means of sanitizing a filename.
+//   While the resulting filename itself would be legal, it doesn't necessarily
+//   mean that the file will behave safely. On Windows, certain reserved names
+//   refer to devices rather than files (E.g. LPT1), and some filenames could be
+//   interpreted as shell namespace extensions (E.g. Foo.{<GUID>}).
+//
+// TODO(asanka): Move full filename sanitization logic here.
 BASE_I18N_EXPORT void ReplaceIllegalCharactersInPath(
     FilePath::StringType* file_name,
     char replace_char);
 
 // Compares two filenames using the current locale information. This can be
 // used to sort directory listings. It behaves like "operator<" for use in
 // std::sort.
 BASE_I18N_EXPORT bool LocaleAwareCompareFilenames(const FilePath& a,
                                                   const FilePath& b);
 
 // Calculates the canonical file-system representation of |file_name| base name.
 // Modifies |file_name| in place. No-op if not on ChromeOS.
 BASE_I18N_EXPORT void NormalizeFileNameEncoding(FilePath* file_name);
 
 }  // namespace i18n
 }  // namespace base
 
 #endif  // BASE_I18N_FILE_UTIL_ICU_H_