Added volume adjust sound behind the flag.

media/audio/sounds/wav_reader.cc

Index: media/audio/sounds/wav_reader.cc
diff --git a/media/audio/sounds/wav_reader.cc b/media/audio/sounds/wav_reader.cc
new file mode 100644
index 0000000000000000000000000000000000000000..1e03e6d002c5b0bf631bdfa2cd659c912eec12ef
--- /dev/null
+++ b/media/audio/sounds/wav_reader.cc
@@ -0,0 +1,45 @@
+// 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.
+
+#include "media/audio/sounds/wav_reader.h"
+
+#include "base/logging.h"
+#include "media/base/audio_bus.h"
+
+namespace media {
+
+WavReaderImpl::WavReaderImpl(const WavParser& wav_parser)
+    : wav_parser_(wav_parser) {}
+
+WavReaderImpl::~WavReaderImpl() {}
+
+bool WavReaderImpl::AtEnd(size_t cursor) {
+  return wav_parser_.data().size() <= cursor;
+}
+
+bool WavReaderImpl::CopyTo(AudioBus* bus,
+                           size_t cursor,
+                           size_t* bytes_written) {
+  if (!bus)
+    return false;
+  if (bus->channels() != wav_parser_.num_channels()) {
+    VLOG(1) << "Number of channel mismatch.";
+    return false;
+  }
+  if (AtEnd(cursor)) {
+    bus->Zero();
+    return true;
+  }
+  const base::StringPiece& data = wav_parser_.data();
+  const int remaining_frames =
+      (data.size() - cursor) / wav_parser_.bytes_per_frame();
+  const int frames = std::min(bus->frames(), remaining_frames);
+  bus->FromInterleaved(data.data() + cursor, frames,
+                       wav_parser_.bytes_per_sample());
+  *bytes_written = frames * wav_parser_.bytes_per_frame();
+  bus->ZeroFramesPartial(frames, bus->frames() - frames);
+  return true;
+}
+
+}  // namespace media