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

chrome/browser/policy/config_dir_policy_provider_unittest.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/compiler_specific.h"
 #include "base/file_util.h"
-#include "base/json/json_value_serializer.h"
+#include "base/json/json_string_value_serializer.h"
 #include "base/message_loop.h"
 #include "base/scoped_temp_dir.h"
 #include "base/string_number_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/policy/config_dir_policy_provider.h"
 #include "chrome/browser/policy/configuration_policy_provider_test.h"
 
 namespace policy {
 
 namespace {
@@ skipping 157 matching lines @@
                                          POLICY_LEVEL_MANDATORY,
                                          POLICY_SCOPE_USER);
   scoped_ptr<PolicyMap> policy(loader.Load());
   EXPECT_TRUE(policy.get());
   PolicyMap expected;
   expected.LoadFrom(&test_dict_foo, POLICY_LEVEL_MANDATORY, POLICY_SCOPE_USER);
   EXPECT_TRUE(policy->Equals(expected));
 }
 
 }  // namespace policy