Use a direct include of strings headers in base/.

base/threading/worker_pool_posix.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/threading/worker_pool_posix.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/debug/trace_event.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
-#include "base/stringprintf.h"
+#include "base/strings/stringprintf.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread_local.h"
 #include "base/threading/worker_pool.h"
 #include "base/tracked_objects.h"
 
 using tracked_objects::TrackedTime;
 
 namespace base {
 
 namespace {
@@ skipping 171 matching lines @@
       return PendingTask(FROM_HERE, base::Closure());
     }
   }
 
   PendingTask pending_task = pending_tasks_.front();
   pending_tasks_.pop();
   return pending_task;
 }
 
 }  // namespace base