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

chrome/common/json_value_serializer_perftest.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 <vector>
 
 #include "base/file_util.h"
-#include "base/json/json_value_serializer.h"
+#include "base/json/json_string_value_serializer.h"
 #include "base/path_service.h"
 #include "base/perftimer.h"
 #include "base/string_util.h"
 #include "base/values.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/logging_chrome.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
 class JSONValueSerializerTests : public testing::Test {
@@ skipping 62 matching lines @@
     }
   }
   chrome_timer.Done();
 
   // Clean up test cases.
   for (size_t i = 0; i < test_cases.size(); ++i) {
     delete test_cases[i];
     test_cases[i] = NULL;
   }
 }