Optimize phishing page term feature extraction.

base/i18n/case_conversion.cc

 // Copyright (c) 2011 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 "base/i18n/case_conversion.h"
 
 #include "unicode/unistr.h"
 
 namespace base {
 namespace i18n {
 
-string16 ToLower(const string16& string) {
-  icu::UnicodeString unicode_string(string.c_str(), string.size());
+string16 ToLower(const WideStringPiece& string) {
+  icu::UnicodeString unicode_string(string.data(), string.size());
   unicode_string.toLower();
   return string16(unicode_string.getBuffer(), unicode_string.length());
 }
 
-string16 ToUpper(const string16& string) {
-  icu::UnicodeString unicode_string(string.c_str(), string.size());
+string16 ToUpper(const WideStringPiece& string) {
+  icu::UnicodeString unicode_string(string.data(), string.size());
   unicode_string.toUpper();
   return string16(unicode_string.getBuffer(), unicode_string.length());
 }
 
 }  // namespace i18n
 }  // namespace base