Make base compile with no "using base::FilePath".

base/json/json_file_value_serializer.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_file_value_serializer.h"
 
 #include "base/file_util.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/logging.h"
 
+using base::FilePath;
+
 const char* JSONFileValueSerializer::kAccessDenied = "Access denied.";
 const char* JSONFileValueSerializer::kCannotReadFile = "Can't read file.";
 const char* JSONFileValueSerializer::kFileLocked = "File locked.";
 const char* JSONFileValueSerializer::kNoSuchFile = "File doesn't exist.";
 
 bool JSONFileValueSerializer::Serialize(const Value& root) {
   return SerializeInternal(root, false);
 }
 
 bool JSONFileValueSerializer::SerializeAndOmitBinaryValues(const Value& root) {
@@ skipping 66 matching lines @@
       *error_code = error;
     if (error_str)
       *error_str = GetErrorMessageForCode(error);
     return NULL;
   }
 
   JSONStringValueSerializer serializer(json_string);
   serializer.set_allow_trailing_comma(allow_trailing_comma_);
   return serializer.Deserialize(error_code, error_str);
 }