Send data from mixer to APM limiter more often.

webrtc/modules/audio_mixer/audio_mixer_impl.cc

Index: webrtc/modules/audio_mixer/audio_mixer_impl.cc
diff --git a/webrtc/modules/audio_mixer/audio_mixer_impl.cc b/webrtc/modules/audio_mixer/audio_mixer_impl.cc
index d9e195174c75b44853fedc880f09746425ea9659..188dc13e9301e0fb1d4f531e4cca1f4d276d350c 100644
--- a/webrtc/modules/audio_mixer/audio_mixer_impl.cc
+++ b/webrtc/modules/audio_mixer/audio_mixer_impl.cc
@@ -141,8 +141,10 @@ void AudioMixerImpl::Mix(size_t number_of_channels,
 
   {
     rtc::CritScope lock(&crit_);
+    const int number_of_streams = audio_source_list_.size();
     frame_combiner_.Combine(GetAudioFromSources(), number_of_channels,
-                            OutputFrequency(), audio_frame_for_mixing);
+                            OutputFrequency(), number_of_streams,
+                            audio_frame_for_mixing);
   }
 
   return;