Refactor StringPiece hash.

media/midi/midi_manager_alsa.h

 // Copyright 2014 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 MEDIA_MIDI_MIDI_MANAGER_ALSA_H_
 #define MEDIA_MIDI_MIDI_MANAGER_ALSA_H_
 
 #include <alsa/asoundlib.h>
 #include <stdint.h>
 #include <map>
 #include <utility>
 #include <vector>
 
+#include "base/containers/hash_tables.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread.h"
 #include "base/values.h"
 #include "device/udev_linux/scoped_udev.h"
 #include "media/midi/midi_export.h"
 #include "media/midi/midi_manager.h"
 
@@ skipping 406 matching lines @@
   bool event_thread_shutdown_ = false;  // guarded by shutdown_lock_
   base::Lock shutdown_lock_;            // guards event_thread_shutdown_
 
   DISALLOW_COPY_AND_ASSIGN(MidiManagerAlsa);
 };
 
 }  // namespace midi
 }  // namespace media
 
 #endif  // MEDIA_MIDI_MIDI_MANAGER_ALSA_H_