Introduce AudioHardwareConfig for renderer side audio device info.

content/renderer/render_thread_impl.h

Index: content/renderer/render_thread_impl.h
diff --git a/content/renderer/render_thread_impl.h b/content/renderer/render_thread_impl.h
index a70be920d098f5f1b3b5861087e91c46fc22fa12..f771d7e4f459e369870ce4f118be1c353cb71229 100644
--- a/content/renderer/render_thread_impl.h
+++ b/content/renderer/render_thread_impl.h
@@ -65,6 +65,7 @@ class MediaStreamCenter;
 class MediaStreamDependencyFactory;
 class P2PSocketDispatcher;
 class PeerConnectionTracker;
+class RendererAudioHardwareConfig;
 class RendererWebKitPlatformSupportImpl;
 class RenderProcessObserver;
 class VideoCaptureImplManager;
@@ -246,6 +247,11 @@ class CONTENT_EXPORT RenderThreadImpl : public RenderThread,
   // first call.
   AudioRendererMixerManager* GetAudioRendererMixerManager();
 
+  // RendererAudioHardwareConfig contains audio hardware configuration for
+  // renderer side clients.  Creation requires a synchronous IPC call so it is

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

Nit, does the sync IPC require lacy init?

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

What do you mean? We use lazy initialization because of the synchronous IPC, we
don't want to block render thread startup.

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

It was not clear to me if "sync IPC ===> lazy init" and what the exact
dependence was. I think I understand what you mean now. It was just how the
comment was formulated that made me confused.

+  // lazily created on the first call.
+  RendererAudioHardwareConfig* GetAudioHardwareConfig();
+
 #if defined(OS_WIN)
   void PreCacheFontCharacters(const LOGFONT& log_font, const string16& str);
 #endif
@@ -381,6 +387,7 @@ class CONTENT_EXPORT RenderThreadImpl : public RenderThread,
   scoped_ptr<WebGraphicsContext3DCommandBufferImpl> gpu_vda_context3d_;
 
   scoped_ptr<AudioRendererMixerManager> audio_renderer_mixer_manager_;
+  scoped_ptr<RendererAudioHardwareConfig> audio_hardware_config_;
 
   HistogramCustomizer histogram_customizer_;