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

ui/views/controls/message_box_view.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 "ui/views/controls/message_box_view.h"
 
 #include "base/i18n/rtl.h"
 #include "base/message_loop.h"
-#include "base/string_split.h"
+#include "base/strings/string_split.h"
 #include "base/utf_string_conversions.h"
 #include "ui/base/accessibility/accessible_view_state.h"
 #include "ui/base/clipboard/clipboard.h"
 #include "ui/base/clipboard/scoped_clipboard_writer.h"
 #include "ui/views/controls/button/checkbox.h"
 #include "ui/views/controls/image_view.h"
 #include "ui/views/controls/label.h"
 #include "ui/views/controls/textfield/textfield.h"
 #include "ui/views/layout/grid_layout.h"
 #include "ui/views/layout/layout_constants.h"
@@ skipping 250 matching lines @@
   if (checkbox_) {
     layout->AddPaddingRow(0, inter_row_vertical_spacing_);
     layout->StartRow(0, checkbox_column_view_set_id);
     layout->AddView(checkbox_);
   }
 
   layout->AddPaddingRow(0, inter_row_vertical_spacing_);
 }
 
 }  // namespace views