Added volume adjust sound behind the flag.

media/audio/sounds/wav_reader.h

Index: media/audio/sounds/wav_reader.h
diff --git a/media/audio/sounds/wav_reader.h b/media/audio/sounds/wav_reader.h
new file mode 100644
index 0000000000000000000000000000000000000000..2b02871f841d9fd370e0c87d7f817468d114d851
--- /dev/null
+++ b/media/audio/sounds/wav_reader.h
@@ -0,0 +1,46 @@
+// Copyright 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 MEDIA_AUDIO_SOUNDS_WAV_READER_H_
+#define MEDIA_AUDIO_SOUNDS_WAV_READER_H_
+
+#include "base/compiler_specific.h"
+#include "media/audio/sounds/wav_parser.h"
+
+namespace media {
+
+class AudioBus;
+
+class MEDIA_EXPORT WavReader {
+ public:
+  WavReader() {}
+  virtual ~WavReader() {}
+
+  // Returns true when cursor points to the end of the track.
+  virtual bool AtEnd(size_t cursor) = 0;
+
+  // Copies the audio data to |bus| starting from the |cursor| and in
+  // the case of success stores the number of written bytes in
+  // |bytes_written|. |bytes_written| should not be NULL.
+  virtual bool CopyTo(AudioBus* bus, size_t cursor, size_t* bytes_written) = 0;
+};
+
+class MEDIA_EXPORT WavReaderImpl : public WavReader {
+ public:
+  explicit WavReaderImpl(const WavParser& wav_parser);
+  virtual ~WavReaderImpl();
+
+  // WavReader implementation:
+  virtual bool AtEnd(size_t cursor) OVERRIDE;
+  virtual bool CopyTo(AudioBus* bus,
+                      size_t cursor,
+                      size_t* bytes_written) OVERRIDE;
+
+ private:
+  WavParser wav_parser_;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_SOUNDS_WAV_READER_H_