Use a direct include of strings headers in chrome/test/.

chrome/test/gpu/gpu_pixel_browsertest.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/command_line.h"
 #include "base/file_util.h"
 #include "base/files/file_enumerator.h"
 #include "base/files/file_path.h"
 #include "base/path_service.h"
-#include "base/string_util.h"
-#include "base/stringprintf.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/window_snapshot/window_snapshot.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/chrome_version_info.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "chrome/test/base/test_launcher_utils.h"
 #include "chrome/test/base/tracing.h"
 #include "chrome/test/base/ui_test_utils.h"
@@ skipping 518 matching lines @@
     {160, 100, 0, 0, 0}
   };
   const size_t ref_pixel_count = sizeof(ref_pixels) / sizeof(ReferencePixel);
 
   gfx::Size container_size(400, 300);
   base::FilePath url =
       test_data_dir().AppendASCII("pixel_canvas2d.html");
   RunPixelTest(container_size, url, ref_img_revision_update,
                ref_pixels, ref_pixel_count);
 }