Candidate fix for a crash at shutdown when the IO thread is going away. More details in the bug rep…

media/audio/audio_output_device.cc

Index: media/audio/audio_output_device.cc
diff --git a/media/audio/audio_output_device.cc b/media/audio/audio_output_device.cc
index d432103ce06112cc8fda0a0575fb3f39545ed416..eff1a0cbc0156af26ce966560fdedafd34f84c53 100644
--- a/media/audio/audio_output_device.cc
+++ b/media/audio/audio_output_device.cc
@@ -142,8 +142,11 @@ void AudioOutputDevice::ShutDownOnIOThread() {
   if (stream_id_) {
     is_started_ = false;
 
-    ipc_->CloseStream(stream_id_);
-    ipc_->RemoveDelegate(stream_id_);
+    if (ipc_) {
+      ipc_->CloseStream(stream_id_);
+      ipc_->RemoveDelegate(stream_id_);
+    }
+
     stream_id_ = 0;
   }