Break two classes defined in json_value_serializer.cc, .h into separate files.

chrome/browser/extensions/convert_web_app.cc

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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 "chrome/browser/extensions/convert_web_app.h"
 
 #include <cmath>
 #include <limits>
 #include <string>
 #include <vector>
 
 #include "base/base64.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
-#include "base/json/json_value_serializer.h"
+#include "base/json/json_file_value_serializer.h"
 #include "base/logging.h"
 #include "base/path_service.h"
 #include "base/scoped_temp_dir.h"
 #include "base/stringprintf.h"
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/common/extensions/extension_file_util.h"
@@ skipping 157 matching lines @@
       extension_flags,
       &error);
   if (!extension) {
     LOG(ERROR) << error;
     return NULL;
   }
 
   temp_dir.Take();  // The caller takes ownership of the directory.
   return extension;
 }