Made AudioReceiveStream a mixer participant.

webrtc/audio/audio_receive_stream.h

Index: webrtc/audio/audio_receive_stream.h
diff --git a/webrtc/audio/audio_receive_stream.h b/webrtc/audio/audio_receive_stream.h
index 871d48d6b0101472e6db82b63eaba408c5b9f8cd..06018c040a1c6304e8b02368a38c375527327efd 100644
--- a/webrtc/audio/audio_receive_stream.h
+++ b/webrtc/audio/audio_receive_stream.h
@@ -18,6 +18,7 @@
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/base/thread_checker.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_header_parser.h"
+#include "webrtc/modules/audio_mixer/audio_mixer_defines.h"
 
 namespace webrtc {
 class CongestionController;
@@ -30,7 +31,8 @@ class ChannelProxy;
 
 namespace internal {
 
-class AudioReceiveStream final : public webrtc::AudioReceiveStream {
+class AudioReceiveStream final : public webrtc::AudioReceiveStream,
+                                 public MixerAudioSource {

[the sun, 2016/10/03 11:41:26]

Multiple inheritance with implementation classes is a slippery slope. Can we
make MixerAudioSource a pure interface before we do this?

Also, the *public* mix_history_ *pointer* in MixerAudioSource is a dangerous
construct. It seems to me MixerAudioSource should be split up into a) the
interface and b) the object containing the mix state for AudioMixerImpl. The
latter would be internal to AudioMixerImpl.

[aleloi, 2016/10/03 12:57:28]

ossu@ has pointed out the naked pointer problems a while ago. I have made a CL
that removes mix_history_ a dependency. webrtc::AudioReceiveStream is a pure
interface, so this is strictly speaking a no-multiple-inheritance rule violation
(at least not yet).

Splitting MixerAudioSource in two would have consequence on the way participants
can find out if they are mixed or not. Now a participant can call
this->WasMixed(). If I remove that, the functionality could either be moved to
AudioMixer or maybe be dropped completely. I think it's better to remove it
completely since it's not used anywhere.

  public:
   AudioReceiveStream(CongestionController* congestion_controller,
                      const webrtc::AudioReceiveStream::Config& config,
@@ -52,6 +54,10 @@ class AudioReceiveStream final : public webrtc::AudioReceiveStream {
                   const PacketTime& packet_time);
   const webrtc::AudioReceiveStream::Config& config() const;
 
+  // MixerAudioSource
+  AudioFrameWithMuted GetAudioFrameWithMuted(int32_t id,
+                                             int sample_rate_hz) override;
+
  private:
   VoiceEngine* voice_engine() const;