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

chrome/test/automation/automation_json_requests.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/test/automation/automation_json_requests.h"
 
 #include "base/basictypes.h"
 #include "base/file_path.h"
 #include "base/format_macros.h"
 #include "base/json/json_reader.h"
-#include "base/json/json_value_serializer.h"
+#include "base/json/json_string_value_serializer.h"
 #include "base/json/json_writer.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/stringprintf.h"
 #include "base/test/test_timeouts.h"
 #include "base/time.h"
 #include "base/values.h"
 #include "chrome/common/automation_messages.h"
 #include "chrome/test/automation/automation_proxy.h"
 
 using automation::Error;
@@ skipping 859 matching lines @@
     base::Value* value,
     Error* error) {
   DictionaryValue dict;
   dict.SetString("command", "SetPrefs");
   dict.SetInteger("windex", 0);
   dict.SetString("path", pref);
   dict.Set("value", value);
   DictionaryValue reply_dict;
   return SendAutomationJSONRequest(sender, dict, &reply_dict, error);
 }