Corrected the behavior in AEC3 during buffer overruns and underruns

webrtc/modules/audio_processing/aec3/shadow_filter_update_gain.cc

Index: webrtc/modules/audio_processing/aec3/shadow_filter_update_gain.cc
diff --git a/webrtc/modules/audio_processing/aec3/shadow_filter_update_gain.cc b/webrtc/modules/audio_processing/aec3/shadow_filter_update_gain.cc
index 85bc11fb0d631865cc45ec2e25b019aa047b3509..61a1f575b13b5062f6304781705d63d1a2a16f69 100644
--- a/webrtc/modules/audio_processing/aec3/shadow_filter_update_gain.cc
+++ b/webrtc/modules/audio_processing/aec3/shadow_filter_update_gain.cc
@@ -17,6 +17,13 @@
 
 namespace webrtc {
 
+void ShadowFilterUpdateGain::HandleEchoPathChange() {
+  // TODO(peah): Check whether this counter should instead be initialized to a
+  // large value.
+  poor_signal_excitation_counter_ = 0;
+  call_counter_ = 0;
+}
+
 void ShadowFilterUpdateGain::Compute(
     const RenderBuffer& render_buffer,
     const RenderSignalAnalyzer& render_signal_analyzer,