Link things together and enable the device selection for linux and mac.

content/renderer/media/audio_input_device.cc

Index: content/renderer/media/audio_input_device.cc
diff --git a/content/renderer/media/audio_input_device.cc b/content/renderer/media/audio_input_device.cc
index ce0da67909c755374acfe4540bdaad9ddc862211..80a84150f4f2f3f944e87c1c89b1066e545dce3f 100644
--- a/content/renderer/media/audio_input_device.cc
+++ b/content/renderer/media/audio_input_device.cc
@@ -13,6 +13,8 @@
 #include "content/renderer/render_thread_impl.h"
 #include "media/audio/audio_util.h"
 
+static const char kDefaultDeviceUId[] = "default";

[scherkus (not reviewing), 2011/11/16 01:20:40]

I don't see this used and it's also confusing with the code change below where
you pass in "" as default

[no longer working on chromium, 2011/11/16 17:45:48]

Sorry, wrong code by mistake.

+
 AudioInputDevice::AudioInputDevice(size_t buffer_size,
                                    int channels,
                                    double sample_rate,
@@ -126,8 +128,10 @@ void AudioInputDevice::InitializeOnIOThread() {
   // otherwise it will send a AudioInputHostMsg_StartDevice msg to the browser
   // and create the stream when getting a OnDeviceReady() callback.
   if (!session_id_) {
+    // Pass an empty string to indicate using default device.
+    std::string default_device_uid = "";
     Send(new AudioInputHostMsg_CreateStream(stream_id_, audio_parameters_,
-                                            true));
+                                            true, default_device_uid));
   } else {
     Send(new AudioInputHostMsg_StartDevice(stream_id_, session_id_));
     pending_device_ready_ = true;
@@ -246,27 +250,28 @@ void AudioInputDevice::OnStateChanged(AudioStreamState state) {
   }
 }
 
-void AudioInputDevice::OnDeviceReady(int index) {
+void AudioInputDevice::OnDeviceReady(const std::string& device_uid) {
   DCHECK(MessageLoop::current() == ChildProcess::current()->io_message_loop());
-  VLOG(1) << "OnDeviceReady (index=" << index << ")";
+  VLOG(1) << "OnDeviceReady (device_uid=" << device_uid << ")";
 
   // Takes care of the case when Stop() is called before OnDeviceReady().
   if (!pending_device_ready_)
     return;
 
-  // -1 means no device has been started.
-  if (index == -1) {
+  // If AudioInputDeviceManager returns an empty string, it means no device
+  // is ready for start.
+  if (device_uid.empty()) {
     filter_->RemoveDelegate(stream_id_);
     stream_id_ = 0;
   } else {
     Send(new AudioInputHostMsg_CreateStream(
-        stream_id_, audio_parameters_, true));
+        stream_id_, audio_parameters_, true, device_uid));
   }
 
   pending_device_ready_ = false;
   // Notify the client that the device has been started.
   if (event_handler_)
-    event_handler_->OnDeviceStarted(index);
+    event_handler_->OnDeviceStarted(device_uid);
 }
 
 void AudioInputDevice::Send(IPC::Message* message) {