Revert of Drop the 16kHz sample rate restriction on AECM and zero out higher bands

webrtc/voice_engine/transmit_mixer.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 1128 matching lines @@
 
   // We want to process at the lowest rate possible without losing information.
   // Choose the lowest native rate at least equal to the input and codec rates.
   const int min_processing_rate = std::min(sample_rate_hz, codec_rate);
   for (size_t i = 0; i < AudioProcessing::kNumNativeSampleRates; ++i) {
     _audioFrame.sample_rate_hz_ = AudioProcessing::kNativeSampleRatesHz[i];
     if (_audioFrame.sample_rate_hz_ >= min_processing_rate) {
       break;
     }
   }
+  if (audioproc_->echo_control_mobile()->is_enabled()) {
+    // AECM only supports 8 and 16 kHz.
+    _audioFrame.sample_rate_hz_ = std::min(
+        _audioFrame.sample_rate_hz_, AudioProcessing::kMaxAECMSampleRateHz);
+  }
   _audioFrame.num_channels_ = std::min(num_channels, num_codec_channels);
   RemixAndResample(audio, samples_per_channel, num_channels, sample_rate_hz,
                    &resampler_, &_audioFrame);
 }
 
 int32_t TransmitMixer::RecordAudioToFile(
     uint32_t mixingFrequency)
 {
     rtc::CritScope cs(&_critSect);
     if (_fileRecorderPtr == NULL)
@@ skipping 166 matching lines @@
 void TransmitMixer::EnableStereoChannelSwapping(bool enable) {
   swap_stereo_channels_ = enable;
 }
 
 bool TransmitMixer::IsStereoChannelSwappingEnabled() {
   return swap_stereo_channels_;
 }
 
 }  // namespace voe
 }  // namespace webrtc