Correction of the AEC3 underrun behavior and minor other corrections

webrtc/modules/audio_processing/aec3/render_delay_buffer.cc

Index: webrtc/modules/audio_processing/aec3/render_delay_buffer.cc
diff --git a/webrtc/modules/audio_processing/aec3/render_delay_buffer.cc b/webrtc/modules/audio_processing/aec3/render_delay_buffer.cc
index cf3e2482ef7f5f364a5d3de371a0dc94f17bf562..6e6766ab4ded9a17104fe99c664049f0abafc98d 100644
--- a/webrtc/modules/audio_processing/aec3/render_delay_buffer.cc
+++ b/webrtc/modules/audio_processing/aec3/render_delay_buffer.cc
@@ -124,6 +124,11 @@ void RenderDelayBufferImpl::Reset() {
   downsampled_render_buffer_.buffer.fill(0.f);
   fft_buffer_.Clear();
   api_call_jitter_buffer_.Reset();
+  for (auto& c : buffer_) {
+    for (auto& b : c) {
+      std::fill(b.begin(), b.end(), 0.f);
+    }
+  }
 }
 
 bool RenderDelayBufferImpl::Insert(