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

webrtc/modules/audio_processing/audio_processing_impl.cc

Index: webrtc/modules/audio_processing/audio_processing_impl.cc
diff --git a/webrtc/modules/audio_processing/audio_processing_impl.cc b/webrtc/modules/audio_processing/audio_processing_impl.cc
index 66123962c3a87468357b4b006665bd8b6ea6d02d..a7c120f3956b13f0c4a798a71f961453979dc213 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl.cc
+++ b/webrtc/modules/audio_processing/audio_processing_impl.cc
@@ -118,6 +118,7 @@
     arraysize(AudioProcessing::kNativeSampleRatesHz);
 const int AudioProcessing::kMaxNativeSampleRateHz = AudioProcessing::
     kNativeSampleRatesHz[AudioProcessing::kNumNativeSampleRates - 1];
+const int AudioProcessing::kMaxAECMSampleRateHz = kSampleRate16kHz;
 
 AudioProcessing* AudioProcessing::Create() {
   Config config;
@@ -364,7 +365,7 @@
 
   formats_.api_format = config;
 
-  // We process at the closest native rate >= min(input rate, output rate).
+  // We process at the closest native rate >= min(input rate, output rate)...
   const int min_proc_rate =
       std::min(formats_.api_format.input_stream().sample_rate_hz(),
                formats_.api_format.output_stream().sample_rate_hz());
@@ -374,6 +375,11 @@
     if (fwd_proc_rate >= min_proc_rate) {
       break;
     }
+  }
+  // ...with one exception.
+  if (public_submodules_->echo_control_mobile->is_enabled() &&
+      min_proc_rate > kMaxAECMSampleRateHz) {
+    fwd_proc_rate = kMaxAECMSampleRateHz;
   }
 
   capture_nonlocked_.fwd_proc_format = StreamConfig(fwd_proc_rate);
@@ -608,6 +614,12 @@
       frame->sample_rate_hz_ != kSampleRate32kHz &&
       frame->sample_rate_hz_ != kSampleRate48kHz) {
     return kBadSampleRateError;
+  }
+
+  if (public_submodules_->echo_control_mobile->is_enabled() &&
+      frame->sample_rate_hz_ > kMaxAECMSampleRateHz) {
+    LOG(LS_ERROR) << "AECM only supports 16 or 8 kHz sample rates";
+    return kUnsupportedComponentError;
   }
 
   ProcessingConfig processing_config;