Make UTF8ToWide take a StringPiece, to avoid copying to a std::string.

base/string_util_icu.cc

 // Copyright (c) 2006-2008 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/string_util.h"
 
 #include <string.h>
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 180 matching lines @@
 bool WideToUTF8(const wchar_t* src, size_t src_len, std::string* output) {
   if (src_len == 0) {
     output->clear();
     return true;
   }
 
   ReserveUTF8Output(src, src_len, output);
   return ConvertUnicode<wchar_t, std::string>(src, src_len, output);
 }
 
-std::wstring UTF8ToWide(const std::string& utf8) {
+std::wstring UTF8ToWide(const StringPiece& utf8) {
   std::wstring ret;
   if (utf8.empty())
     return ret;
 
   UTF8ToWide(utf8.data(), utf8.length(), &ret);
   return ret;
 }
 
 bool UTF8ToWide(const char* src, size_t src_len, std::wstring* output) {
   if (src_len == 0) {
@@ skipping 311 matching lines @@
   u_strToWCS(buffer, 64, &length, ustr.getBuffer(), ustr.length() , &error);
   if (U_FAILURE(error)) {
     NOTREACHED();
     // As a fallback, just return the raw number in a string.
     return StringPrintf(L"%lld", number);
   }
   return std::wstring(buffer, static_cast<std::wstring::size_type>(length));
 #endif  // defined(WCHAR_T_IS_UTF32)
 }