Notify NetEqController during muted state.

During muted state NetEq shortcircuits a large part of the internals to
quickly return a buffer filled with zeros. It can be beneficial for the
controller to be aware that it is in muted state.

Bug: webrtc:11005
Change-Id: I5fe24b4a3704d953cbd68b5a24bbb7ef58b30be0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/186760
Commit-Queue: Ivo Creusen <ivoc@webrtc.org>
Reviewed-by: Jakob Ivarsson <jakobi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32330}

api/neteq/neteq_controller.h

@@ -163,6 +163,10 @@ class NetEqController {
                                             uint32_t main_timestamp,
                                             int fs_hz) = 0;
 
+  // Notify the NetEqController that we are currently in muted state.
+  // TODO(ivoc): Make pure virtual when downstream is updated.
+  virtual void NotifyMutedState() {}
+
   // Returns true if a peak was found.
   virtual bool PeakFound() const = 0;
 

modules/audio_coding/neteq/decision_logic.h

@@ -84,6 +84,8 @@ class DecisionLogic : public NetEqController {
 
   void RegisterEmptyPacket() override { delay_manager_->RegisterEmptyPacket(); }
 
+  void NotifyMutedState() override {}
+
   bool SetMaximumDelay(int delay_ms) override {
     return delay_manager_->SetMaximumDelay(delay_ms);
   }

modules/audio_coding/neteq/neteq_impl.cc

@@ -857,6 +857,7 @@ int NetEqImpl::GetAudioInternal(AudioFrame* audio_frame,
                   static_cast<uint32_t>(audio_frame->samples_per_channel_);
     audio_frame->num_channels_ = sync_buffer_->Channels();
     stats_->ExpandedNoiseSamples(output_size_samples_, false);
+    controller_->NotifyMutedState();
     *muted = true;
     return 0;
   }