Adding full initial version of delay estimation functionality in echo canceller 3

webrtc/modules/audio_processing/aec3/block_processor.cc

Index: webrtc/modules/audio_processing/aec3/block_processor.cc
diff --git a/webrtc/modules/audio_processing/aec3/block_processor.cc b/webrtc/modules/audio_processing/aec3/block_processor.cc
index 1f50a84854de85df938aa6023ac3d5364c23bfa6..550a21073fc8d980be2ddab04352a73d5203113a 100644
--- a/webrtc/modules/audio_processing/aec3/block_processor.cc
+++ b/webrtc/modules/audio_processing/aec3/block_processor.cc
@@ -61,7 +61,9 @@ BlockProcessorImpl::BlockProcessorImpl(
       sample_rate_hz_(sample_rate_hz),
       render_buffer_(std::move(render_buffer)),
       delay_controller_(std::move(delay_controller)),
-      echo_remover_(std::move(echo_remover)) {}
+      echo_remover_(std::move(echo_remover)) {
+  RTC_DCHECK(ValidFullBandRate(sample_rate_hz_));
+}
 
 BlockProcessorImpl::~BlockProcessorImpl() = default;