src/: Update the remaining include paths of string_split.h to its new location.

ui/aura/bench/bench_main.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/at_exit.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/i18n/icu_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
-#include "base/string_split.h"
+#include "base/strings/string_split.h"
 #include "base/time.h"
 #include "third_party/khronos/GLES2/gl2.h"
 #include "third_party/skia/include/core/SkXfermode.h"
 #include "ui/aura/client/default_capture_client.h"
 #include "ui/aura/env.h"
 #include "ui/aura/focus_manager.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/test/test_screen.h"
 #include "ui/aura/window.h"
 #include "ui/base/hit_test.h"
@@ skipping 336 matching lines @@
 
   root_window->ShowRootWindow();
   MessageLoopForUI::current()->Run();
   focus_client.reset();
   root_window.reset();
 
   ui::CompositorTestSupport::Terminate();
 
   return 0;
 }