Use a direct include of strings headers in chrome/browser/chromeos/.

chrome/browser/chromeos/drive/search_metadata_unittest.cc

 // Copyright (c) 2013 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 "chrome/browser/chromeos/drive/search_metadata.h"
 
 #include "base/files/scoped_temp_dir.h"
 #include "base/message_loop.h"
-#include "base/stringprintf.h"
+#include "base/strings/stringprintf.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/chromeos/drive/fake_free_disk_space_getter.h"
 #include "chrome/browser/chromeos/drive/file_cache.h"
 #include "chrome/browser/chromeos/drive/file_system_util.h"
 #include "chrome/browser/chromeos/drive/test_util.h"
 #include "content/public/test/test_browser_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace drive {
 namespace internal {
@@ skipping 593 matching lines @@
 }
 
 TEST(SearchMetadataSimpleTest, FindAndHighlight_MoreMetaChars) {
   std::string highlighted_text;
   EXPECT_TRUE(FindAndHighlight("a&b&c&d", "b&c", &highlighted_text));
   EXPECT_EQ("a&amp;<b>b&amp;c</b>&amp;d", highlighted_text);
 }
 
 }  // namespace internal
 }  // namespace drive