Robustify the AEC3 inaudible echo detection

webrtc/modules/audio_processing/aec3/residual_echo_estimator.cc

Index: webrtc/modules/audio_processing/aec3/residual_echo_estimator.cc
diff --git a/webrtc/modules/audio_processing/aec3/residual_echo_estimator.cc b/webrtc/modules/audio_processing/aec3/residual_echo_estimator.cc
index f3b310657dbc81ca4ed778c884ab732cc628ca36..c5df82c747933c2cdba19049939bd7a5c449a3fd 100644
--- a/webrtc/modules/audio_processing/aec3/residual_echo_estimator.cc
+++ b/webrtc/modules/audio_processing/aec3/residual_echo_estimator.cc
@@ -144,7 +144,8 @@ void ResidualEchoEstimator::Estimate(
   }
 
   // If the echo is deemed inaudible, set the residual echo to zero.
-  if (aec_state.InaudibleEcho()) {
+  if (aec_state.InaudibleEcho() &&
+      (aec_state.ExternalDelay() || aec_state.HeadsetDetected())) {
     R2->fill(0.f);
   }