Added metric for the delay in AEC3.

Bug: webrtc:8569
Change-Id: I659049a411654bd3a252ab29008fac467f903efd
Reviewed-on: https://webrtc-review.googlesource.com/25600
Commit-Queue: Per Åhgren <peah@webrtc.org>
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20892}
diff --git a/modules/audio_processing/include/audio_processing.h b/modules/audio_processing/include/audio_processing.h
index 6c8f4db..d3a1ef5 100644
--- a/modules/audio_processing/include/audio_processing.h
+++ b/modules/audio_processing/include/audio_processing.h
@@ -912,6 +912,7 @@
   struct Metrics {
     double echo_return_loss;
     double echo_return_loss_enhancement;
+    int delay_ms;
   };
 
   // Collect current metrics from the echo controller.