Robustified the detection of linear filter quality in AEC3

webrtc/modules/audio_processing/aec3/aec_state.cc

Index: webrtc/modules/audio_processing/aec3/aec_state.cc
diff --git a/webrtc/modules/audio_processing/aec3/aec_state.cc b/webrtc/modules/audio_processing/aec3/aec_state.cc
index ccb8639472c8f4f5c82867f79d71c300f4d5dce9..cc344abca0bdc953e2d7768136b30378976f2c3e 100644
--- a/webrtc/modules/audio_processing/aec3/aec_state.cc
+++ b/webrtc/modules/audio_processing/aec3/aec_state.cc
@@ -175,7 +175,7 @@ void AecState::Update(const std::vector<std::array<float, kFftLengthBy2Plus1>>&
       (!echo_saturation_) &&
       (!render_received_ ||
        blocks_with_filter_adaptation_ > kEchoPathChangeConvergenceBlocks) &&
-      filter_delay_ && echo_path_change_counter_ <= 0;
+      filter_delay_ && echo_path_change_counter_ <= 0 && external_delay_;
 
   // After an amount of active render samples for which an echo should have been
   // detected in the capture signal if the ERL was not infinite, flag that a