Use a direct include of strings headers in base/.

base/prefs/json_pref_store_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/prefs/json_pref_store.h"
 
 #include "base/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/path_service.h"
 #include "base/run_loop.h"
-#include "base/string_util.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/threading/thread.h"
 #include "base/values.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 namespace {
 
@@ skipping 260 matching lines @@
   RunLoop().RunUntilIdle();
 
   // Compare to expected output.
   base::FilePath golden_output_file =
       data_dir_.AppendASCII("write.golden.need_empty_value.json");
   ASSERT_TRUE(file_util::PathExists(golden_output_file));
   EXPECT_TRUE(file_util::TextContentsEqual(golden_output_file, pref_file));
 }
 
 }  // namespace base