Avoid a string copy in URLRequestResourceBundleJob::GetData().

base/strings/string_util.cc

 // Copyright 2013 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/strings/string_util.h"
 
 #include <ctype.h>
 #include <errno.h>
 #include <math.h>
 #include <stdarg.h>
@@ skipping 388 matching lines @@
 bool IsStringASCII(const string16& str) {
   return DoIsStringASCII(str.data(), str.length());
 }
 
 #if defined(WCHAR_T_IS_UTF32)
 bool IsStringASCII(const std::wstring& str) {
   return DoIsStringASCII(str.data(), str.length());
 }
 #endif
 
-bool IsStringUTF8(const std::string& str) {
+bool IsStringUTF8(const StringPiece& str) {
   const char *src = str.data();
   int32 src_len = static_cast<int32>(str.length());
   int32 char_index = 0;
 
   while (char_index < src_len) {
     int32 code_point;
     CBU8_NEXT(src, char_index, src_len, code_point);
     if (!IsValidCharacter(code_point))
       return false;
   }
@@ skipping 529 matching lines @@
 }
 
 }  // namespace
 
 size_t base::strlcpy(char* dst, const char* src, size_t dst_size) {
   return lcpyT<char>(dst, src, dst_size);
 }
 size_t base::wcslcpy(wchar_t* dst, const wchar_t* src, size_t dst_size) {
   return lcpyT<wchar_t>(dst, src, dst_size);
 }