Use a direct include of strings headers in chromeos/.

chromeos/audio/audio_device.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 "chromeos/audio/audio_device.h"
 
 #include "base/format_macros.h"
-#include "base/stringprintf.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 
 namespace {
 
 // Get the priority for a particular device type. The priority returned
 // will be between 0 to 3, the higher number meaning a higher priority.
 uint8 GetDevicePriority(chromeos::AudioDeviceType type) {
   switch (type) {
     // Fall through.
     case chromeos::AUDIO_TYPE_HEADPHONE:
@@ skipping 98 matching lines @@
                       "active = %s ",
                       active ? "true" : "false");
   base::StringAppendF(&result,
                       "plugged_time= %s ",
                       base::Uint64ToString(plugged_time).c_str());
 
   return result;
 }
 
 }  // namespace chromeos