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

media/audio/audio_input_device.cc

Index: media/audio/audio_input_device.cc
diff --git a/media/audio/audio_input_device.cc b/media/audio/audio_input_device.cc
index 381af19c22878230da3e998918b55759512dcb10..401042acf26d8cded7a7f25fd12611a238620a61 100644
--- a/media/audio/audio_input_device.cc
+++ b/media/audio/audio_input_device.cc
@@ -253,8 +253,10 @@ void AudioInputDevice::ShutDownOnIOThread() {
   // NOTE: |completion| may be NULL.
   // Make sure we don't call shutdown more than once.
   if (stream_id_) {
-    ipc_->CloseStream(stream_id_);
-    ipc_->RemoveDelegate(stream_id_);
+    if (ipc_) {
+      ipc_->CloseStream(stream_id_);
+      ipc_->RemoveDelegate(stream_id_);
+    }
 
     stream_id_ = 0;
     session_id_ = 0;