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

ui/views/widget/tooltip_manager.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 "ui/views/widget/tooltip_manager.h"
 
 #include <vector>
 
-#include "base/string_split.h"
+#include "base/strings/string_split.h"
 #include "base/utf_string_conversions.h"
 #include "ui/base/text/text_elider.h"
 
 namespace {
 
 // Maximum number of characters we allow in a tooltip.
 const size_t kMaxTooltipLength = 1024;
 
 // Maximum number of lines we allow in the tooltip.
 const size_t kMaxLines = 6;
@@ skipping 36 matching lines @@
         ui::ElideText(*i, font, available_width, ui::ELIDE_AT_END);
     *max_width = std::max(*max_width, font.GetStringWidth(elided_text));
     if (!result.empty())
       result.push_back('\n');
     result.append(elided_text);
   }
   *text = result;
 }
 
 }  // namespace views