Add new decoding statistics for muted output

This change adds a new statistic for logging how many calls to
NetEq::GetAudio resulted in a "muted output". A muted output happens
if the packet stream has been dead for some time (and the last decoded
packet was not comfort noise).

BUG=webrtc:5606
BUG=b/31256483

Review-Url: https://codereview.webrtc.org/2341293002
Cr-Commit-Position: refs/heads/master@{#14302}
diff --git a/webrtc/modules/audio_coding/acm2/call_statistics.cc b/webrtc/modules/audio_coding/acm2/call_statistics.cc
index 4441932..7ac9fc4 100644
--- a/webrtc/modules/audio_coding/acm2/call_statistics.cc
+++ b/webrtc/modules/audio_coding/acm2/call_statistics.cc
@@ -10,14 +10,18 @@
 
 #include "webrtc/modules/audio_coding/acm2/call_statistics.h"
 
-#include <assert.h>
+#include "webrtc/base/checks.h"
 
 namespace webrtc {
 
 namespace acm2 {
 
-void CallStatistics::DecodedByNetEq(AudioFrame::SpeechType speech_type) {
+void CallStatistics::DecodedByNetEq(AudioFrame::SpeechType speech_type,
+                                    bool muted) {
   ++decoding_stat_.calls_to_neteq;
+  if (muted) {
+    ++decoding_stat_.decoded_muted_output;
+  }
   switch (speech_type) {
     case AudioFrame::kNormalSpeech: {
       ++decoding_stat_.decoded_normal;
@@ -37,7 +41,7 @@
     }
     case AudioFrame::kUndefined: {
       // If the audio is decoded by NetEq, |kUndefined| is not an option.
-      assert(false);
+      RTC_NOTREACHED();
     }
   }
 }