Refactor the Get*Hardware* routines a bit.

content/renderer/media/audio_device.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.
 //
 // Low-latency audio rendering unit utilizing audio output stream provided
 // by browser process through IPC.
 //
 // Relationship of classes.
 //
 //  AudioOutputController                AudioDevice
@@ skipping 83 matching lines @@
   // Sets the playback volume, with range [0.0, 1.0] inclusive.
   // Returns |true| on success.
   bool SetVolume(double volume);
 
   // Gets the playback volume, with range [0.0, 1.0] inclusive.
   void GetVolume(double* volume);
 
   double sample_rate() const { return sample_rate_; }
   size_t buffer_size() const { return buffer_size_; }
 
-  static double GetAudioHardwareSampleRate();
-  static size_t GetAudioHardwareBufferSize();
-
   // Methods called on IO thread ----------------------------------------------
   // AudioMessageFilter::Delegate methods, called by AudioMessageFilter.
   virtual void OnRequestPacket(AudioBuffersState buffers_state);
   virtual void OnStateChanged(AudioStreamState state);
   virtual void OnCreated(base::SharedMemoryHandle handle, uint32 length);
   virtual void OnLowLatencyCreated(base::SharedMemoryHandle handle,
                                    base::SyncSocket::Handle socket_handle,
                                    uint32 length);
   virtual void OnVolume(double volume);
 
@@ skipping 51 matching lines @@
   int32 stream_id_;
 
   // Data transfer between browser and render process uses a combination
   // of sync sockets and shared memory to provide lowest possible latency.
   scoped_ptr<base::SharedMemory> shared_memory_;
   scoped_ptr<base::SyncSocket> socket_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(AudioDevice);
 };
 
+// Contains static methods to query hardware properties from the browser

[henrika (OOO until Aug 14), 2011/11/17 12:27:44]

Namespace perhaps?

+// process. Values are cached to avoid unnecessary round trips, but the cache
+// can be cleared if needed (currently only used by tests).
+class CONTENT_EXPORT AudioHardware {
+ public:
+  static double GetOutputSampleRate();
+  static double GetInputSampleRate();
+  static size_t GetOutputBufferSize();
+
+  // Forces the next call to any of the Get functions to query the hardware
+  // and repopulate the cache.
+  static void ResetCache();
+
+ private:
+  static double output_sample_rate_;
+  static double input_sample_rate_;
+  static size_t output_buffer_size_;
+
+  // This class doesn't support construction.
+  DISALLOW_COPY_AND_ASSIGN(AudioHardware);
+};
+
 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_DEVICE_H_