Use StringPiece for UTF string conversions.

base/strings/utf_string_conversions.h

 // 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.
 
 #ifndef BASE_STRINGS_UTF_STRING_CONVERSIONS_H_
 #define BASE_STRINGS_UTF_STRING_CONVERSIONS_H_
 
 #include <string>
 
 #include "base/base_export.h"
@@ skipping 15 matching lines @@
                             std::wstring* output);
 BASE_EXPORT std::wstring UTF8ToWide(const StringPiece& utf8);
 
 BASE_EXPORT bool WideToUTF16(const wchar_t* src, size_t src_len,
                              string16* output);
 BASE_EXPORT string16 WideToUTF16(const std::wstring& wide);
 BASE_EXPORT bool UTF16ToWide(const char16* src, size_t src_len,
                              std::wstring* output);
 BASE_EXPORT std::wstring UTF16ToWide(const string16& utf16);
 
-BASE_EXPORT bool UTF8ToUTF16(const char* src, size_t src_len, string16* output);
+BASE_EXPORT bool UTF8ToUTF16(const StringPiece& utf8, string16* output);
 BASE_EXPORT string16 UTF8ToUTF16(const StringPiece& utf8);
-BASE_EXPORT bool UTF16ToUTF8(const char16* src, size_t src_len,
-                             std::string* output);
+BASE_EXPORT bool UTF16ToUTF8(const StringPiece16& utf16, std::string* output);
 BASE_EXPORT std::string UTF16ToUTF8(const string16& utf16);
 
 // We are trying to get rid of wstring as much as possible, but it's too big
 // a mess to do it all at once.  These conversions should be used when we
 // really should just be passing a string16 around, but we haven't finished
 // porting whatever module uses wstring and the conversion is being used as a
 // stopcock.  This makes it easy to grep for the ones that should be removed.
 #if defined(OS_WIN)
 # define WideToUTF16Hack
 # define UTF16ToWideHack
@@ skipping 13 matching lines @@
 using base::WideToUTF8;
 using base::UTF8ToWide;
 using base::WideToUTF16;
 using base::UTF16ToWide;
 using base::UTF8ToUTF16;
 using base::UTF16ToUTF8;
 using base::ASCIIToWide;
 using base::ASCIIToUTF16;
 
 #endif  // BASE_STRINGS_UTF_STRING_CONVERSIONS_H_