Update JSONReader to take base::StringPiece instead of std::string

base/json/json_reader.cc

 // Copyright (c) 2012 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/json/json_reader.h"
 
 #include "base/json/json_parser.h"
 #include "base/logging.h"
 
 namespace base {
@@ skipping 20 matching lines @@
 }
 
 JSONReader::JSONReader(int options)
     : parser_(new internal::JSONParser(options)) {
 }
 
 JSONReader::~JSONReader() {
 }
 
 // static
-Value* JSONReader::Read(const std::string& json) {
+Value* JSONReader::Read(const StringPiece& json) {
   internal::JSONParser parser(JSON_PARSE_RFC);
   return parser.Parse(json);
 }
 
 // static
-Value* JSONReader::Read(const std::string& json,
+Value* JSONReader::Read(const StringPiece& json,
                         int options) {
   internal::JSONParser parser(options);
   return parser.Parse(json);
 }
 
 // static
-Value* JSONReader::ReadAndReturnError(const std::string& json,
+Value* JSONReader::ReadAndReturnError(const StringPiece& json,
                                       int options,
                                       int* error_code_out,
                                       std::string* error_msg_out) {
   internal::JSONParser parser(options);
   Value* root = parser.Parse(json);
   if (root)
     return root;
 
   if (error_code_out)
     *error_code_out = parser.error_code();
@@ skipping 36 matching lines @@
 
 JSONReader::JsonParseError JSONReader::error_code() const {
   return parser_->error_code();
 }
 
 std::string JSONReader::GetErrorMessage() const {
   return parser_->GetErrorMessage();
 }
 
 }  // namespace base