Propagate muted info from VoE Channel to AudioConferenceMixer

webrtc/modules/audio_conference_mixer/include/audio_conference_mixer_defines.h

Index: webrtc/modules/audio_conference_mixer/include/audio_conference_mixer_defines.h
diff --git a/webrtc/modules/audio_conference_mixer/include/audio_conference_mixer_defines.h b/webrtc/modules/audio_conference_mixer/include/audio_conference_mixer_defines.h
index 5d58f42435ef6ee6cfc302b3dcd57b74e744a075..e1c5aedc8870eda6f8869b5aa65e23c1438bd6e2 100644
--- a/webrtc/modules/audio_conference_mixer/include/audio_conference_mixer_defines.h
+++ b/webrtc/modules/audio_conference_mixer/include/audio_conference_mixer_defines.h
@@ -11,6 +11,7 @@
 #ifndef WEBRTC_MODULES_AUDIO_CONFERENCE_MIXER_INCLUDE_AUDIO_CONFERENCE_MIXER_DEFINES_H_
 #define WEBRTC_MODULES_AUDIO_CONFERENCE_MIXER_INCLUDE_AUDIO_CONFERENCE_MIXER_DEFINES_H_
 
+#include "webrtc/base/checks.h"
 #include "webrtc/modules/include/module_common_types.h"
 #include "webrtc/typedefs.h"
 
@@ -25,8 +26,34 @@ public:
     // audio every time it's called.
     //
     // If it returns -1, the frame will not be added to the mix.
+    //
+    // NOTE: This function should not be called. It will remain for a short
+    // time so that subclasses can override it without getting warnings.
+    // TODO(henrik.lundin) Remove this function.
     virtual int32_t GetAudioFrame(int32_t id,
-                                  AudioFrame* audioFrame) = 0;
+                                  AudioFrame* audioFrame) {
+      RTC_CHECK(false);
+      return -1;
+    }
+
+
+    // The implementation of GetAudioFrameWithMuted should update audio_frame
+    // with new audio every time it's called. The return value will be
+    // interpreted as follows.
+    enum class AudioFrameInfo {
+      kNormal,  // The samples in audio_frame are valid and should be used.
+      kMuted,   // The samples in audio_frame should not be used, but should be
+                // implicitly interpreted as zero. Other fields in audio_frame
+                // may be read and should contain meaningful values.
+      kError    // audio_frame will not be used.
+    };
+
+    virtual AudioFrameInfo GetAudioFrameWithMuted(int32_t id,
+                                                  AudioFrame* audio_frame) {
+      return GetAudioFrame(id, audio_frame) == -1 ?
+          AudioFrameInfo::kError :
+          AudioFrameInfo::kNormal;
+    }
 
     // Returns true if the participant was mixed this mix iteration.
     bool IsMixed() const;