Introduce AudioHardwareConfig for renderer side audio device info.

content/common/media/audio_messages.h

Index: content/common/media/audio_messages.h
diff --git a/content/common/media/audio_messages.h b/content/common/media/audio_messages.h
index cac43d1e1436f9ef525df152a767c0c9cb792292..49be377a089a5e8de4f9f99d430498a629d9ac33 100644
--- a/content/common/media/audio_messages.h
+++ b/content/common/media/audio_messages.h
@@ -63,6 +63,13 @@ IPC_MESSAGE_CONTROL4(AudioInputMsg_NotifyStreamCreated,
                      uint32 /* length */)
 #endif
 
+// Notification message sent from AudioRendererHost to renderer after an output
+// device change has occurred.
+IPC_MESSAGE_CONTROL3(AudioMsg_NotifyDeviceChanged,
+                     int /* stream id */,
+                     int /* new buffer size */,
+                     int /* new sample rate */)
+
 // Notification message sent from AudioRendererHost to renderer for state
 // update after the renderer has requested a Create/Start/Close.
 IPC_MESSAGE_CONTROL2(AudioMsg_NotifyStreamStateChanged,