Move getUserMedia finish to "when audio track configured".

content/renderer/media/media_stream_audio_track.cc

Index: content/renderer/media/media_stream_audio_track.cc
diff --git a/content/renderer/media/media_stream_audio_track.cc b/content/renderer/media/media_stream_audio_track.cc
index cb64f8af18db392cdee6789560a9c5e0659857c3..788854d042b544a11cfd300357e654490057245e 100644
--- a/content/renderer/media/media_stream_audio_track.cc
+++ b/content/renderer/media/media_stream_audio_track.cc
@@ -118,6 +118,18 @@ void MediaStreamAudioTrack::Stop() {
 }
 
 void MediaStreamAudioTrack::OnSetFormat(const media::AudioParameters& params) {
+  base::OnceCallback<void()> temp_callback;
+  // Call the callback if present, but don't hold a lock while doing so.
+  {
+    base::AutoLock guard(format_set_guard_);
+    format_is_set_ = true;
+    if (!format_set_callback_.is_null()) {
+      temp_callback = std::move(format_set_callback_);
+    }
+  }
+  if (!temp_callback.is_null()) {
+    std::move(temp_callback).Run();
+  }
   deliverer_.OnSetFormat(params);
 }
 
@@ -141,10 +153,14 @@ void MediaStreamAudioTrack::OnData(const media::AudioBus& audio_bus,
   }
 }
 
+bool MediaStreamAudioTrack::format_is_set() {
+  base::AutoLock guard(format_set_guard_);
+  return format_is_set_;
+}
+
 void MediaStreamAudioTrack::getSettings(
     blink::WebMediaStreamTrack::Settings& settings) {
-  // TODO(hta): Extract the real value.
-  settings.deviceId = blink::WebString("audio device ID");
+  DCHECK(format_is_set());
 }
 
 }  // namespace content