Added a new echo likelihood stat that reports the maximum value from a previous time period.

webrtc/call/audio_send_stream.h

Index: webrtc/call/audio_send_stream.h
diff --git a/webrtc/call/audio_send_stream.h b/webrtc/call/audio_send_stream.h
index 20635890649b077e0742654d126c922116af7b00..42914301911968878d4559a91ac7336c7d622c47 100644
--- a/webrtc/call/audio_send_stream.h
+++ b/webrtc/call/audio_send_stream.h
@@ -52,6 +52,7 @@ class AudioSendStream {
     int32_t echo_return_loss = -100;
     int32_t echo_return_loss_enhancement = -100;
     float residual_echo_likelihood = -1.0f;
+    float residual_echo_likelihood_recent_max = -1.0f;
     bool typing_noise_detected = false;
   };