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

chrome/browser/download/download_query_unittest.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 <string>
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/stl_util.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "base/time.h"
 #include "base/values.h"
 #include "chrome/browser/download/download_query.h"
 #include "content/public/test/mock_download_item.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using ::testing::Return;
 using ::testing::ReturnRef;
 using ::testing::_;
@@ skipping 560 matching lines @@
   base::Time start = base::Time::Now();
   Search();
   base::Time end = base::Time::Now();
   double nanos = (end - start).InMillisecondsF() * 1000.0 * 1000.0;
   double nanos_per_item = nanos / static_cast<double>(kNumItems);
   double nanos_per_item_per_filter = nanos_per_item
     / static_cast<double>(kNumFilters);
   std::cout << "Search took " << nanos_per_item_per_filter
             << " nanoseconds per item per filter.\n";
 }