Use a direct include of strings headers in chromeos/.

chromeos/audio/audio_device.h

 // 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.
 
 #ifndef CHROMEOS_AUDIO_AUDIO_DEVICE_H_
 #define CHROMEOS_AUDIO_AUDIO_DEVICE_H_
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "chromeos/chromeos_export.h"
 #include "chromeos/dbus/audio_node.h"
 
 namespace chromeos {
 
 // Ordered from the highest priority to the lowest.
 enum AudioDeviceType {
   AUDIO_TYPE_HEADPHONE,
   AUDIO_TYPE_MIC,
   AUDIO_TYPE_USB,
@@ skipping 37 matching lines @@
       return true;
     } else {
       return false;
     }
   }
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_AUDIO_AUDIO_DEVICE_H_