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

content/renderer/media/audio_input_message_filter.cc

Index: content/renderer/media/audio_input_message_filter.cc
diff --git a/content/renderer/media/audio_input_message_filter.cc b/content/renderer/media/audio_input_message_filter.cc
index f84e8cc2668040b6f525cf26b417fff57d1f1762..8f6a083e71600fb010b0d0d3db2d768431e2981a 100644
--- a/content/renderer/media/audio_input_message_filter.cc
+++ b/content/renderer/media/audio_input_message_filter.cc
@@ -113,14 +113,15 @@ void AudioInputMessageFilter::OnStreamStateChanged(
   delegate->OnStateChanged(state);
 }
 
-void AudioInputMessageFilter::OnDeviceStarted(int stream_id, int index) {
+void AudioInputMessageFilter::OnDeviceStarted(int stream_id,
+                                              const std::string& device_uid) {
   Delegate* delegate = delegates_.Lookup(stream_id);
   if (!delegate) {
     DLOG(WARNING) << "Got audio stream event for a non-existent or removed"
         " audio renderer.";
     return;
   }
-  delegate->OnDeviceReady(index);
+  delegate->OnDeviceReady(device_uid);
 }
 
 int32 AudioInputMessageFilter::AddDelegate(Delegate* delegate) {