Corrected the number of channels used when AEC3 is run on stereo input.

webrtc/modules/audio_processing/audio_processing_impl.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 707 matching lines @@
   return formats_.render_processing_format.num_channels();
 }
 
 size_t AudioProcessingImpl::num_input_channels() const {
   // Used as callback from submodules, hence locking is not allowed.
   return formats_.api_format.input_stream().num_channels();
 }
 
 size_t AudioProcessingImpl::num_proc_channels() const {
   // Used as callback from submodules, hence locking is not allowed.
-  return capture_nonlocked_.beamformer_enabled ? 1 : num_output_channels();
+  return (capture_nonlocked_.beamformer_enabled ||
+          capture_nonlocked_.echo_canceller3_enabled)
+             ? 1
+             : num_output_channels();
 }
 
 size_t AudioProcessingImpl::num_output_channels() const {
   // Used as callback from submodules, hence locking is not allowed.
   return formats_.api_format.output_stream().num_channels();
 }
 
 void AudioProcessingImpl::set_output_will_be_muted(bool muted) {
   rtc::CritScope cs(&crit_capture_);
   capture_.output_will_be_muted = muted;
@@ skipping 1264 matching lines @@
       previous_agc_level(0),
       echo_path_gain_change(false) {}
 
 AudioProcessingImpl::ApmCaptureState::~ApmCaptureState() = default;
 
 AudioProcessingImpl::ApmRenderState::ApmRenderState() = default;
 
 AudioProcessingImpl::ApmRenderState::~ApmRenderState() = default;
 
 }  // namespace webrtc