Move ReadFileToString to the base namespace.

base/json/json_file_value_serializer.h

 // 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.
 
 #ifndef BASE_JSON_JSON_FILE_VALUE_SERIALIZER_H_
 #define BASE_JSON_JSON_FILE_VALUE_SERIALIZER_H_
 
 #include <string>
 
 #include "base/base_export.h"
@@ skipping 59 matching lines @@
   void set_allow_trailing_comma(bool new_value) {
     allow_trailing_comma_ = new_value;
   }
 
  private:
   bool SerializeInternal(const base::Value& root, bool omit_binary_values);
 
   base::FilePath json_file_path_;
   bool allow_trailing_comma_;
 
-  // A wrapper for file_util::ReadFileToString which returns a non-zero
-  // JsonFileError if there were file errors.
+  // A wrapper for ReadFileToString which returns a non-zero JsonFileError if
+  // there were file errors.
   int ReadFileToString(std::string* json_string);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSONFileValueSerializer);
 };
 
 #endif  // BASE_JSON_JSON_FILE_VALUE_SERIALIZER_H_