Introduce AudioHardwareConfig for renderer side audio device info.

content/renderer/media/audio_renderer_mixer_manager.cc

Index: content/renderer/media/audio_renderer_mixer_manager.cc
diff --git a/content/renderer/media/audio_renderer_mixer_manager.cc b/content/renderer/media/audio_renderer_mixer_manager.cc
index 71fafcbdd81ca6a6835dcc0e7c2b7526251ab495..d6e88c8b6de952bf0c4d87627b3fd4adbbe0104c 100644
--- a/content/renderer/media/audio_renderer_mixer_manager.cc
+++ b/content/renderer/media/audio_renderer_mixer_manager.cc
@@ -8,15 +8,15 @@
 #include "base/bind_helpers.h"
 #include "content/renderer/media/audio_device_factory.h"
 #include "content/renderer/media/renderer_audio_output_device.h"
+#include "media/base/audio_hardware_config.h"
 #include "media/base/audio_renderer_mixer.h"
 #include "media/base/audio_renderer_mixer_input.h"
 
 namespace content {
 
-AudioRendererMixerManager::AudioRendererMixerManager(int hardware_sample_rate,
-                                                     int hardware_buffer_size)
-    : hardware_sample_rate_(hardware_sample_rate),
-      hardware_buffer_size_(hardware_buffer_size),
+AudioRendererMixerManager::AudioRendererMixerManager(
+    media::AudioHardwareConfig* hardware_config)
+    : hardware_config_(hardware_config),
       sink_for_testing_(NULL) {
 }
 
@@ -57,7 +57,7 @@ media::AudioRendererMixer* AudioRendererMixerManager::GetMixer(
 #if defined(OS_LINUX)
   int sample_rate = params.sample_rate();
 #else
-  int sample_rate = hardware_sample_rate_;
+  int sample_rate = hardware_config_->GetOutputSampleRate();
 #endif
 
   // Create output parameters based on the audio hardware configuration for
@@ -65,7 +65,7 @@ media::AudioRendererMixer* AudioRendererMixerManager::GetMixer(
   // know that works well for WebAudio and WebRTC.
   media::AudioParameters output_params(
       media::AudioParameters::AUDIO_PCM_LOW_LATENCY, params.channel_layout(),
-      sample_rate, 16, hardware_buffer_size_);
+      sample_rate, 16, hardware_config_->GetOutputBufferSize());

[miu, 2013/01/29 04:55:43]

It's not intuitive to me why we can ignore the hardware's requested sample rate
for Linux/ChromeOS (line 58 above), but not the output buffer size.  Isn't the
calculation of the latter based on the former?

[DaleCurtis, 2013/01/29 19:36:00]

Not on Linux, it's just a fixed 2048.

 
   // If we've created invalid output parameters, simply pass on the input params
   // and let the browser side handle automatic fallback.