Optimize phishing page term feature extraction.

base/i18n/case_conversion.h

Index: base/i18n/case_conversion.h
diff --git a/base/i18n/case_conversion.h b/base/i18n/case_conversion.h
index ecbfba159acca16ac137a324ed27356e48e307b3..73dd862c0218f9c2f641ddbb6ca031a343068a33 100644
--- a/base/i18n/case_conversion.h
+++ b/base/i18n/case_conversion.h
@@ -6,16 +6,16 @@
 #define BASE_I18N_CASE_CONVERSION_H_
 #pragma once
 
-#include "base/string16.h"
+#include "base/string_piece.h"
 
 namespace base {
 namespace i18n {
 
 // Returns the lower case equivalent of string. Uses ICU's default locale.
-string16 ToLower(const string16& string);
+string16 ToLower(const StringPiece16& string);
 
 // Returns the upper case equivalent of string. Uses ICU's default locale.
-string16 ToUpper(const string16& string);
+string16 ToUpper(const StringPiece16& string);
 
 }  // namespace i18n
 }  // namespace base