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

BUG=webrtc:6797

Review-Url: https://codereview.webrtc.org/2629563003
Cr-Commit-Position: refs/heads/master@{#16079}
diff --git a/webrtc/audio/audio_send_stream.cc b/webrtc/audio/audio_send_stream.cc
index aff605f..3831b8d 100644
--- a/webrtc/audio/audio_send_stream.cc
+++ b/webrtc/audio/audio_send_stream.cc
@@ -210,6 +210,8 @@
       audio_processing_stats.echo_return_loss_enhancement.instant();
   stats.residual_echo_likelihood =
       audio_processing_stats.residual_echo_likelihood;
+  stats.residual_echo_likelihood_recent_max =
+      audio_processing_stats.residual_echo_likelihood_recent_max;
 
   internal::AudioState* audio_state =
       static_cast<internal::AudioState*>(audio_state_.get());