Introduce AudioHardwareConfig for renderer side audio device info.

media/base/audio_hardware_config.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 MEDIA_BASE_AUDIO_HARDWARE_CONFIG_H_
+#define MEDIA_BASE_AUDIO_HARDWARE_CONFIG_H_
+
+#include "media/base/channel_layout.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+// Interface for providing access to the audio hardware configuration from the
+// renderer side.  Browser side clients should query the methods in audio_util
+// directly.
+class MEDIA_EXPORT AudioHardwareConfig {
+ public:
+  // Accessors for the currently cached hardware configuration.
+  virtual int GetOutputBufferSize() = 0;
+  virtual int GetOutputSampleRate() = 0;
+  virtual int GetInputSampleRate() = 0;
+  virtual ChannelLayout GetInputChannelLayout() = 0;
+

[henrika (OOO until Aug 14), 2013/01/29 10:46:49]

Two methods are excluded (UpdateOutput/InputConfig) compared with the design
doc. I assume there is a good reason for it.

[DaleCurtis, 2013/01/30 01:31:06]

You brought up a good point and with some creativity, I've collapsed
RendererAudioHardwareConfig and AudioHardwareConfig into one.  Now
RenderThreadImpl takes care of the render-thread-ish parts and
AudioHardwareConfig is just a dumb thread safe wrapper class.

[henrika (OOO until Aug 14), 2013/01/30 10:10:06]

Great.

+ protected:
+  virtual ~AudioHardwareConfig() {}
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_AUDIO_HARDWARE_CONFIG_H_