Refactor the Get*Hardware* routines a bit.

content/renderer/media/audio_hardware.h

+// Copyright (c) 2011 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 CONTENT_RENDERER_MEDIA_AUDIO_HARDWARE_H_
+#define CONTENT_RENDERER_MEDIA_AUDIO_HARDWARE_H_
+#pragma once
+
+#include "base/basictypes.h"
+#include "content/common/content_export.h"
+
+// Contains static methods to query hardware properties from the browser
+// process. Values are cached to avoid unnecessary round trips, but the cache
+// can be cleared if needed (currently only used by tests).
+namespace audio_hardware {
+
+// Fetch the sample rate of the default audio output end point device.
+// Must be called from RenderThreadImpl::current().
+CONTENT_EXPORT double GetOutputSampleRate();
+
+// Fetch the sample rate of the default audio input end point device.
+// Must be called from RenderThreadImpl::current().
+CONTENT_EXPORT double GetInputSampleRate();
+
+// Fetch the buffer size we use for the default output device.
+// Must be called from RenderThreadImpl::current().
+CONTENT_EXPORT size_t GetOutputBufferSize();
+
+// Forces the next call to any of the Get functions to query the hardware
+// and repopulate the cache.
+CONTENT_EXPORT void ResetCache();
+}  // namespace audio_hardware
+
+#endif  // CONTENT_RENDERER_MEDIA_AUDIO_HARDWARE_H_