Use a direct include of strings headers in chrome/browser/r*-s*/.

chrome/browser/sessions/session_backend_unittest.cc

 // Copyright (c) 2011 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/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/stl_util.h"
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "chrome/browser/sessions/session_backend.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
 
 typedef std::vector<SessionCommand*> SessionCommands;
 
 struct TestData {
   SessionCommand::id_type command_id;
   std::string data;
@@ skipping 181 matching lines @@
   backend = NULL;
   backend = new SessionBackend(BaseSessionService::SESSION_RESTORE, path_);
   backend->ReadLastSessionCommandsImpl(&commands);
 
   // And make sure we get back the expected data.
   ASSERT_EQ(1U, commands.size());
   AssertCommandEqualsData(second_data, commands[0]);
 
   STLDeleteElements(&commands);
 }