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

chrome/browser/component_updater/component_unpacker.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 "chrome/browser/component_updater/component_unpacker.h"
 
 #include <string>
 #include <vector>
 
 #include "base/file_util.h"
-#include "base/json/json_value_serializer.h"
+#include "base/json/json_file_value_serializer.h"
 #include "base/memory/scoped_handle.h"
 #include "base/string_number_conversions.h"
 #include "base/stringprintf.h"
 #include "chrome/browser/extensions/sandboxed_extension_unpacker.h"
 #include "chrome/browser/component_updater/component_updater_service.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/common/zip.h"
 #include "crypto/secure_hash.h"
 #include "crypto/signature_verifier.h"
 
@@ skipping 179 matching lines @@
   }
   // Installation successful. The directory is not our concern now.
   unpack_path_.clear();
 }
 
 ComponentUnpacker::~ComponentUnpacker() {
   if (!unpack_path_.empty()) {
     file_util::Delete(unpack_path_, true);
   }
 }