Add an optional artificial nearend signal for aecdump call recreation

webrtc/modules/audio_processing/test/audio_processing_simulator.cc

Index: webrtc/modules/audio_processing/test/audio_processing_simulator.cc
diff --git a/webrtc/modules/audio_processing/test/audio_processing_simulator.cc b/webrtc/modules/audio_processing/test/audio_processing_simulator.cc
index ddfc562aafba474f8e8c05d8385a7d0445b391fa..37ab468b64600f2ff9d83dfeed0352d4c0a7a44b 100644
--- a/webrtc/modules/audio_processing/test/audio_processing_simulator.cc
+++ b/webrtc/modules/audio_processing/test/audio_processing_simulator.cc
@@ -165,6 +165,9 @@ void AudioProcessingSimulator::SetupBuffersConfigsOutputs(
       rtc::CheckedDivExact(input_sample_rate_hz, kChunksPerSecond),
       input_num_channels));
 
+  artificial_nearend_buf_.reset(new ChannelBuffer<float>(
+      rtc::CheckedDivExact(input_sample_rate_hz, kChunksPerSecond), 1));
+
   reverse_in_config_ =
       StreamConfig(reverse_input_sample_rate_hz, reverse_input_num_channels);
   reverse_in_buf_.reset(new ChannelBuffer<float>(