Audio Processing Module: add play-out audio device runtime information

Add a runtime setting that notifies play-out audio device changes.
The payload is a pair indicating a device id and its maximum play-out
volume.

kPlayoutVolumeChange is now forwarded not only to capture, but also
render (required by render_pre_processor).

Bug: webrtc:10608
Change-Id: I8997c207422c1dcd1d53775397d6290939ef3db8
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/159002
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Reviewed-by: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29725}

modules/audio_processing/test/runtime_setting_util.cc

@@ -36,6 +36,11 @@ void ReplayRuntimeSetting(AudioProcessing* apm,
     apm->SetRuntimeSetting(
         AudioProcessing::RuntimeSetting::CreatePlayoutVolumeChange(
             setting.playout_volume_change()));
+  } else if (setting.has_playout_audio_device_change()) {
+    apm->SetRuntimeSetting(
+        AudioProcessing::RuntimeSetting::CreatePlayoutAudioDeviceChange(
+            {setting.playout_audio_device_change().id(),
+             setting.playout_audio_device_change().max_volume()}));
   }
 }
 }  // namespace webrtc