Added the ability to adjust the AEC3 performance for large rooms

webrtc/modules/audio_processing/include/audio_processing.h

Index: webrtc/modules/audio_processing/include/audio_processing.h
diff --git a/webrtc/modules/audio_processing/include/audio_processing.h b/webrtc/modules/audio_processing/include/audio_processing.h
index 05be5feeb199daacf062b85ff9f1e94969f0cd74..6dc6e3fc7673895751da194c8109cd398d97fbe1 100644
--- a/webrtc/modules/audio_processing/include/audio_processing.h
+++ b/webrtc/modules/audio_processing/include/audio_processing.h
@@ -268,6 +268,7 @@ class AudioProcessing : public rtc::RefCountInterface {
     // does not yet have the desired behavior.
     struct EchoCanceller3 {
       bool enabled = false;
+      float echo_decay = 0.f;
     } echo_canceller3;
 
     // Enables the next generation AGC functionality. This feature replaces the