Use a direct include of strings headers in base/.

base/debug/trace_event_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 "base/debug/trace_event_unittest.h"
 
 #include <cstdlib>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/singleton.h"
 #include "base/process_util.h"
-#include "base/stringprintf.h"
+#include "base/strings/stringprintf.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread.h"
 #include "base/values.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using base::debug::HighResSleepForTraceTest;
 
 namespace base {
@@ skipping 1998 matching lines @@
   EXPECT_TRUE(CategoryFilter::IsEmptyOrContainsLeadingOrTrailingWhitespace(
       "   bad_category   "));
   EXPECT_TRUE(CategoryFilter::IsEmptyOrContainsLeadingOrTrailingWhitespace(
       ""));
   EXPECT_FALSE(CategoryFilter::IsEmptyOrContainsLeadingOrTrailingWhitespace(
       "good_category"));
 }
 
 }  // namespace debug
 }  // namespace base