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

webrtc/voice_engine/transmit_mixer.cc

Index: webrtc/voice_engine/transmit_mixer.cc
diff --git a/webrtc/voice_engine/transmit_mixer.cc b/webrtc/voice_engine/transmit_mixer.cc
index a5fa9140f884c9cc5f89d0ec31f47a3479426762..d6a5213217e3bfe92b36a3ddbf6b4f524f6ac0f3 100644
--- a/webrtc/voice_engine/transmit_mixer.cc
+++ b/webrtc/voice_engine/transmit_mixer.cc
@@ -1146,6 +1146,11 @@
       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);