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/float_util.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/stringprintf.h"
@@ skipping 75 matching lines @@
     : start_pos_(NULL),
       json_pos_(NULL),
       end_pos_(NULL),
       stack_depth_(0),
       allow_trailing_comma_(false),
       error_code_(JSON_NO_ERROR),
       error_line_(0),
       error_col_(0) {}
 
 // static
-Value* JSONReader::Read(const std::string& json,
+Value* JSONReader::Read(const StringPiece& json,
                         bool allow_trailing_comma) {
   return ReadAndReturnError(json, allow_trailing_comma, NULL, NULL);
 }
 
 // static
-Value* JSONReader::ReadAndReturnError(const std::string& json,
+Value* JSONReader::ReadAndReturnError(const StringPiece& json,
                                       bool allow_trailing_comma,
                                       int* error_code_out,
                                       std::string* error_msg_out) {
   JSONReader reader = JSONReader();
   Value* root = reader.JsonToValue(json, true, allow_trailing_comma);
   if (root)
     return root;
 
   if (error_code_out)
     *error_code_out = reader.error_code();
@@ skipping 28 matching lines @@
       NOTREACHED();
       return std::string();
   }
 }
 
 std::string JSONReader::GetErrorMessage() const {
   return FormatErrorMessage(error_line_, error_col_,
                             ErrorCodeToString(error_code_));
 }
 
-Value* JSONReader::JsonToValue(const std::string& json, bool check_root,
+Value* JSONReader::JsonToValue(const StringPiece& json, bool check_root,
                                bool allow_trailing_comma) {
   // The input must be in UTF-8.
   if (!IsStringUTF8(json.data())) {
     error_code_ = JSON_UNSUPPORTED_ENCODING;
     return NULL;
   }
 
   start_pos_ = json.data();
   end_pos_ = start_pos_ + json.size();
 
@@ skipping 557 matching lines @@
       ++column_number;
     }
   }
 
   error_line_ = line_number;
   error_col_ = column_number;
   error_code_ = error;
 }
 
 }  // namespace base